Holistic Review: It lacks a bit of storytelling clarity, but with a plot that works as entertainment as well as metaphor, and the welcome return of Osgood and the Zygons, The Zygon Invasion / The Zygon Inversion marks a significant improvement over the author's previous effort.

If you've read my review of Kill the Moon, you will not be surprised to learn that my excitement about an upcoming Zygon episode was severely tempered by the knowledge that it was being written by Peter Harness. After the risible science in his previous episode all but ruined the plot for me, I readily admit that my expectations for this two-parter were not high. On first viewing, I must have missed some of the dialogue — I was watching it with Gray, after all, and we couldn't help commenting on some of the onscreen events — because I found the plot to be quite confusing. My overall impression was that we weren't given enough background to understand what motivated these events; we were just expected to go along for the ride. In some cases, that objection holds true, and I'll discuss a few of my biggest plot concerns below. On subsequent viewings, though, I found that many of my most serious problems had actually been addressed when I wasn't looking. My confusion about which Zygons were evil was actually clarified twice, with the Doctor's lines "I know there are other blobby factions that you don't control." and "This is a splinter group! The rest of the Zygons, the vast majority, they want to live in peace." Even the mysteriously sudden ability of the Zygons to take any form they want is eventually explained by Osgood at the start of part two.

And the plot, for the most part, holds together well. After an entire hatching of 20 million Zygons (most of them patterned after residents of the UK) has been resettled across the Earth, UNIT and the Zygons must preserve their fragile peace by ensuring that the humans never learn of the Zygons' existence. That means that the Zygons not only have to refrain from, you know, killing people, but they also have to remain in disguise for the rest of their lives. At the episode's start, Osgood tries to reassure us that this is how the Zygons have always lived — "They embed themselves in other cultures, and live out their lives in their new bodies, in peace and harmony." — but not only is this version of history completely at odds with what we've seen of the Zygons, and quite certainly not how they lived on their home planet, it's also belied by the degree to which some of the Zygons in this story chafe under that rule. So a splinter group forms, of Zygons who are ready to cast off the shackles of human integration and take over the planet, by any means necessary, with "destroy all humans" being the default option. Naturally, this threatens to blow the coverup wide open and instigate a global war which the Zygons quite possibly won't be able to win, so the Doctor must desperately attempt to preserve the truce and persuade the splinter group to back down.

As it turns out, there are a lot of things that I like about this story, one of them being the way the immigration allegory is handled. Previous stories, like The Unquiet Dead, have been understandably criticized for drawing parallels between immigrants and bloodthirsty conquering aliens, and The Zygon Invasion largely manages to avoid that misstep by presenting a more nuanced version of alien resettlement. Reflecting current news stories, the Zygons are refugees, desperately looking for a place to live, and the Earth, albeit with great reluctance, offers them sanctuary. And it actually works out really well, with the Zygons integrating perfectly into human society, and notably not straining the social services of their host countries or sponging off the government. Part of the reason for this positive message, I'm sure, is that the Zygons look like ordinary British people, so there's no grumbling about them "taking all the jobs", even in foreign countries, as you'd otherwise expect after an influx of 20 million displaced refugees. (Although the Doctor does makes a sly joke on this topic: "Well, you can't have the United Kingdom. There's already people living there. They'll all think you're gonna pinch their benefits.") The only negative comment comes, no surprise, from a US citizen: "We didn't want 'em, they just turned up. No jobs, nowhere to live, no money, and they were... they were odd." Unfortunately, this is the point at which the episode's message starts to get a bit muddled. In this case, the Zygons' reaction to being unmasked is to murder the locals, which only serves to legitimize those prejudiced opinions, echoing my country's (and others') current paranoia about providing asylum to refugees from the Middle East. This puts a rather different spin on Walsh's line "It's not paranoia when it's real.", which at first I really liked, but in retrospect seems to echo those same sentiments.

Part of the problem, of course, is the Zygons are traditionally considered to be Doctor Who "monsters", so it's acceptable and even expected for them to be portrayed as evil. Because they're now additionally filling the role of both refugees and extremists, it's almost impossible not to see parallels in dialogue like those two examples, even if none were intended — although it's also impossible to say with certainty that these messages were not deliberate. Fortunately, the nature of the storyline also means that the Zygons get some astounding shades of grey. According to The Zygon Invasion, most Zygons — like most humans — are inherently good. Aliens that are actually like us??? How will we ever hold onto our anti-monster prejudice now? The Osgoods put this really well: "Any race is capable of the best and the worst. Every race is peaceful and warlike. Good and evil." And I have to say, even though I like my monsters to be evil and I never thought of the Zygons as candidates for rehabilitation, I really like this development. It means we could actually have a Zygon character like Strax someday — although, for that matter, we have one now in the form of new Zygon Osgood, whichever one she is. It also opens up some really interesting possibilities for future stories. I mean, can you imagine what life must be like for Bonnie, hopping from personality to personality, and completely subsuming herself in whichever one she's inhabiting? You'd eventually start to forget who you really were. I guess what I'm anticipating is an episode like Buffy's Selfless, featuring a Zygon in the role of Anya.

Part of what helps the immigration allegory come across as more sensitive is the fact that the "evil" Zygons — a description that's actually very questionable — are likened to fanatical extremists, particularly when Kate mentions "radicalization" in the younger brood, which reinforces the fact that they don't represent all Zygons. The thing is, their complaints are actually very sympathetic. They resent feeling that they constantly have to hide their true selves just to avoid panicking the poor delicate Earth people, which really when you think about it isn't all that different from what, say, pre-op transgender people have to deal with in their daily lives. (This is perhaps where the last remaining parallel becomes relevant, that if a Zygon is forcibly unmasked, life becomes so unbearable that they may be driven to commit suicide.) I've even been hearing similar complaints recently (not new complaints, I'm just out of touch) from African-Americans in our community, who feel that they can't express their full black identity — wearing their hair in braids, or speaking naturally — because white people complain that it makes them "uncomfortable". Uncomfortable, because your hair is in braids! I mean, really. Bonnie also complains that "We've been treated like cattle, we've been left to fend for ourselves." to which the Doctor is, surprisingly, entirely unsympathetic, even though he doesn't refute it. So even though I'm sure the Doctor's assimilation strategy is the wisest move, I absolutely sympathize with the demands of the Zygon splinter group, which is a shrewd move on Harness' part. Unfortunately, the rebels have decided to go about liberating themselves in the worst possible way, by trying to manipulate humanity into starting a war to the death. They don't want to peacefully coexist, they want to conquer. To that end, they establish training camps and they infiltrate communities and they murder people, much like extremists in the news today. They even have a flag that bears a passing resemblance to the white-on-black flag of Daesh, and like Daesh, they attempt to assert their own legitimacy by naming themselves the new Zygon High Command.

Best of all, this is more than just an action story; it has a powerful message, too. Alongside the moral about peaceful coexistence, the end of the story makes some wonderful statements about war. "The only way anyone can live in peace," says the Doctor, "is if they're prepared to forgive." SO TRUE. So, so, so true. And it's followed by this equally-true diatribe, which really hits home:

Doctor: "It's not a game, Kate. This is a scale model of war! Every war ever fought, right there in front of you. Because it's always the same. When you fire that first shot, no matter how right you feel, you have no idea who's going to die! You don't know whose children are going to scream and burn. How many hearts will be broken. How many lives shattered. How much blood will spill until everybody does what they were always going to have to do from the very beginning: sit down and talk!"

So, credit where credit is due: Peter Harness, I hereby relinquish (for the time being) any grave concerns I may have harbored about your writing abilities, and concede that Kill the Moon was probably just an unfortunate fluke. Along with that powerful anti-war speech, Bonnie's interrogation of Clara is written superbly, as Clara continually tries to evade Bonnie's questions while Bonnie tries to nail her down. Generally speaking, the story has two main thrusts: it's an alien-invasion story, and it's an evil-duplicate story. Between the two, I think the alien-invasion angle is handled best. Thanks to the refugee and extremist allegories, it has a stronger hook, and the story is smart to make us at least somewhat emotionally invested in the well-being of the Zygons who just want to live in peace (represented by Osgood and Etoine). The evil-duplicate angle, I think, lacks a bit of that emotional investment. We hear a lot about the danger of Zygon duplicates, but somehow I feel we never really get a sense of what it would feel like to discover that your partner or best friend was a bloodthirsty Zygon. Although, between the revelations about Clara and Sandeep's parents, the story is definitely reaching for that goal, so I can't fault it for not trying. (The surprise about Clara would have completely fooled me, had I not been reading an article on Digital Spy the day before, and saw a link to an article posted on October 31 titled "Are Clara and the Zygons going to exterminate humanity?" So there was always something in the back of my mind wondering why Clara would apparently team up with the Zygons, and when she led UNIT down into the tunnels, I began to get suspicious that she'd been replaced.) Just as with Kill the Moon, I felt that the story got strongest toward the end. (It's an interesting thing, and a rather rare one, to find a writer who's actually better at endings than he is at all the rest. Usually it's the other way around!) But in a pleasant reversal from Kill the Moon, this time I could only find three major things that the story did wrong, and none of them bothers me anywhere near the level that every single one of my complaints about Kill the Moon did.

• I find the "Truth or Consequences" theme in this story to be extremely confusing. It crops up, apparently by crazy random happenstance, in three distinct places: as the campaign slogan (and title) of the newly-formed Zygon splinter group, as the button labels in the Osgood Box(es) that the Doctor created months ago, and as the town in New Mexico (renamed in 1950) where a Zygon refugee community is inadvertently uncovered. I can't figure out a way to tie all three together — ie, there's no one person who's responsible for orchestrating all three appearances of the phrase — so its recurrence feels incredibly and unnaturally forced. The one that grates the most is the town, because the Zygon splinter group doesn't even appear to have been involved with the unmasking, at least initially. That happened completely by accident, as a result of a young Zygon who hadn't mastered how to maintain its bodyprint. In fact, the entire New Mexico thread appears to be completely disconnected from the storyline. Kate visits the town because the Zygon slogan was coincidentally named after it, only to discover that it actually has (coincidentally) been caught in the crossfire of a local human-Zygon war. The only evidence we have that the Zygons in NM were in any way connected with the rebels is that, in an amazing display of coincidental timing, Bonnie contacts the sheriff for an update on the destruction of UNIT almost immediately after Norlander has revealed herself to be a Zygon. Why was Norlander tasked with destroying UNIT if newly-arrived Kate was the only UNIT member around? Difficult to say. Given her familiarity with the history of the local situation, Sheriff Zygon appears to have been in the town for weeks, so she apparently didn't pursue Kate to the US. Maybe Bonnie alerted her that Kate was on the way? Either way, the town of Truth and Consequences could really have been written out without damaging the story; on the contrary, it might have streamlined it. The only two upsides to this plot thread are that, first, it demonstrates the global nature of the Zygon threat, and second, it illustrates exactly the danger that the Doctor's been warning about: apparently, the humans' violent response to the Zygon child did indeed cause all of the Zygons in town to retaliate in self-defense, and send them running straight into the open welcoming arms of the rebel insurgents.

• The secrecy around the Osgood Box really doesn't make any sense. It's dangled as a plot point not because of any internally consistent motivation, but purely to keep the audience guessing. Why does it matter that people believe that there's only one Osgood Box? For example, there's no reason why the two Osgoods make a video half-explaining the Osgood Box. If anybody other than the audience watches it, we certainly don't witness it. My only guess is that the Osgoods knew someone was likely to break the peace treaty, so lured them with the promise of a permanent solution in the hopes of averting mass slaughter... but how would the would-be treaty-breakers have come across this video? And it still doesn't explain why they state that the video will be necessary if one of them dies. How would that affect anything? Likewise, Clara is equally secretive about the answer to the apparently-critical question, "Why is it called the Osgood Box?" Why is it so critical for Bonnie to wait and see that there are duplicate boxes, then run back to speak with Clara again, rather than simply hearing it from Clara the first time? Answer: no reason, it's yet another ploy designed purely for the benefit of the audience at home. But the twist that there's nothing in either box is a relief — I found it difficult to swallow the idea that the Doctor would really have allowed the humans to possess a Zygon-genocide bomb — although for that very reason, the twist was rather predictable.

• My final big beef, and it's admittedly a minor one: Why must the Zygons be "updated" even when it isn't necessary? I'm absolutely in favor of building on what we know about a monster — as the episode does with the revelations about Zygon hatcheries, and their nicely-designed new technology (the smoke bomb, the control polyp, the bodyprint pods, and their communicators) — but only when the new information doesn't contradict what we already know, or thought we knew. In a way, it's similar to what I was saying last week, about monsters having limitations. Let's say you create a monster with no hands, and it's such a wild success that the audience demands its return. If you then bring that monster back for a story which includes some inconvenient doorknobs, you do not get to suddenly reveal that the monster can grow temporary hands if and when necessary, just to save yourself some time. Yes, it's a useful plot shortcut, but it undercuts what we know of the monster, especially if the monster also happens to have a prehensile tongue or tail that could turn the knob just as easily. (UK readers, I apologize for my completely inadvertent mental image involving a prehensile tongue and a knob.) Such is the case with the Zygons' perfectly-serviceable sting being replaced by some kind of peculiar long-distance instantaneously-deadly energy discharge. While I really do love the electrified-hairball effect, which is unexpectedly icky, it just doesn't feel right for the Zygons (and it doesn't help that we saw a similar weapon last week on the Mire ship). This kind of "shortcut upgrade" also tends to feel like a cheat, precisely because it often removes a limitation that the monster previously possessed. It's a bit easier to forgive the replacement of the sting, since it's only ever been unofficial fanon, but it does mean that a Zygon no longer has to touch you in order to injure you. Similarly, we're now informed that the Zygons no longer require hostages in order to maintain a bodyprint (even though we see the rebels taking dozens if not hundreds of hostages for some unexplained reason). On one hand, that's not a bad change, because it means the Zygons could literally be anybody in the world at any time, and at least the new default is explicitly clarified in the dialogue. Presumably it also solves the problem of 20 million Zygons taking the form of UK residents, which could have led to some awkward situations if either (a) they had to kidnap the originals for bodyprints, or (b) they all resettled in the UK, therefore potentially living the next village down from the original. But, again, it does remove a rather interesting limitation, and as such also eliminates some of the dramatic possibilities that come along with the need for Zygon prisoners.

Before we move on to character matters, one final plot comment: it's becoming increasingly obvious that "hybrid" is one of the arc words for this season. We had the Dalek hybrid prophecy in the season opener, followed by immortal human-Mire hybrid Ashildr, and now the Doctor is breathlessly describing the simultaneously human-and-Zygon Osgood as being "like a hybrid!" What does it all mean? How could these completely independent events possibly feed into a season arc? Will they tie directly into the "Minister of War"? Or is it just a season theme, and not an arc? Despite myself, I am intrigued.

Peter Capaldi is given a Doctor-defining moment in his anti-war speeches, which are sure to be remembered with as much fondness as, say, Colin Baker's righteous indignation against the Time Lords. His rockstar personality continues to thrive, this week modernizing "Amazing Grace" on his guitar and giving a paparazzi salute before boarding the plane. Aside from these shining moments, I'm not sure I love how he's written in this story. He's flippant a lot, experimenting with embarrassing pseudonyms ("Doctor Disco", "Doctor Frankenstein" and "Doctor Puntastic") and various accents, and I'm not sure how well flippancy sits with his Doctor. Plus, I can't decide if I like the Doctor's American accent or not. It sounds weird, but not because Capaldi's doing it wrong. I think it just sounds weird to hear a car-salesman accent coming out of his mouth! Otherwise, fantastic delivery of "Doesn't mean I like it!", "I don't understand?", "And when I close my eyes, I hear more screams than anyone could ever be able to count.", the compassion in his eyes as he looks at Bonnie, and "I'll be the judge of time."

The other major highlight of the story for me was Jenna Coleman's performance as Bonnie. It's been ages since we had a good "evil duplicate" story, and Coleman knocks it out of the park with Bonnie's narrow-eyed glare and cool clipped voice. It's just a bit reminiscent of Lillias Walker's performance as Zygon nurse Sister Lamont, which is an excellent comparison to be able to make. Coleman is totally believable as a villain, and she gives an especially good performance during Clara's battle of wits (and pulses) with Bonnie. In hindsight, there are a few clues, especially her oh-so-casual interrogation of Kate ("If you're not gonna negotiate, what are you gonna do?", "How many troops do you have?" and "Have you got any snazzy weapons?"). I wasn't terribly keen on the idea of spending an episode in Clara's dreams, but it's actually done well. Rather than being lost in dreamland, these scenes give Clara the opportunity to interact with Bonnie, and sometimes to witness events from Bonnie's perspective. I'm still not sure I buy this two-way telepathic communication between Zygon and host bodyprint, but I'm glad that for all Clara tries, she can't dramatically affect Bonnie's actions. (I'm not quite sure what was going through her head, though, when she decided that "biting my fingers" might be a useful strategy. How was that supposed to help divert Bonnie's aim?) Her characterization in the story is good, too, with Invasion of the Zygons providing one of her best personality-enlightening quotes yet: "It's a Trivial Pursuit question. I used to memorize Trivial Pursuit questions so I could... win." It's a great fit with her control-freak personality, and it's one of the few times that particular character detail has been shown (or at least implied) rather than told. My favorite Coleman moments: her screams of frustration and rage when Bonnie finds Osgood's video on the laptop, the hilarious winking as Clara tries to communicate with the Doctor through Bonnie, her laugh before "Oh, that scared you, didn't it?", her facial expressions (with gears clearly turning) on "I can't.", and "Well Clara, I think you're reaching the end of your —".

It's also just plain great to see the Zygons again, and holding down a proper story all on their own this time. Their appearance as the main enemy in The Day of the Doctor was thrilling, but the story wasn't really about them in the way that it is here. And even the story's setup, explaining that millions of Zygons now call the Earth home, practically ensures that this isn't the last we've seen of them.

And speaking of seeing people again, Petronella Osgood! What a delight! I love your first name! Fandom was certainly in a deep collective funk after she was killed in Death in Heaven, but, just as some people desperately theorized at the time, Osgood did indeed still have a Zygon duplicate. We don't know, and may never know, which one was killed by Missy, but Osgood repeatedly reiterates the message "it doesn't matter" which, again, is a really nice message to send: it doesn't matter whether I'm the same as you or different, it only matters who I am. And by the story's end, we have two Osgoods again, so double insurance against any further unexpected deaths, yay! (Now if only we could retroactively insert Zygon duplicates of all my other favorite TV characters. I'm thinking of two in particular, from Buffy and The X-Files, who could have really used a Zygon backup in my opinion!) To my great satisfaction, with Clara off being controlled by a Zygon, Osgood gets to fill the companion role in this story, so it's a great opportunity to see what a 12/Osgood partnership might look like. Her characterization seems a tiny bit less endearingly geeky than usual in this story, and a tiny bit more tactless ("You've gone quiet 'cause I mentioned Clara. You think she might be dead." sounds more like a line I'd expect to come out of Cordelia's mouth), but she remains brave-yet-vulnerable, and intelligent (look how quickly she figures out that Clara is probably still alive!), and compassionate, and it's such fun to be in the company of a companion who knows the Doctor's history as well as we do ("You're talking nonsense to distract me from being really scared. It's one of your known character traits."). Her sartorial taste continues to amuse, as here she unashamedly trots out McCoy's question-mark jumper (I mean, really, who ever thought we'd see that onscreen again?!) and Davison's shirt with question-mark collars. (What I really want to know is: do you think they recreated the pullover? Surely it can't have been the original? But how long would it have taken them to knit that from scratch?!) I was desperately encouraging her to join the TARDIS crew at the end, especially once the Doctor actually did issue a formal invitation, but she turned him down!!! I mean, c'mon, is just one trip too much to ask? You could take that much time off from saving the world, surely! I can't help but think that's it's bound to happen at some point.

I find myself with little to say about Kate (Jemma Redgrave). It's always a pleasure to see her, and she's a reliably reassuring presence, so perhaps my lack of commentary is due to the fact that she isn't really given anything new to do in this story. She organizes manoeuvres, she investigates, she fires her gun at bad things, and that's really about it. Standard Kate, but no less enjoyable for it. And I loved Redgrave's emotional delivery of "I'm sorry."

Poor Jac! I had no idea she'd be killed off in the first part; I thought for certain she was being established as a recurring UNIT character. I'll admit that the character wasn't my favorite, only because she hadn't been given much development beyond being funny and clever, but I really enjoyed Jaye Griffiths' performance and the energy that she brought to the role. My favorite of her lines: "They go down, down down down down down down, a few minutes go by, and then... they're all gone."

Colonel Walsh (Rebecca Front) makes a good ally for the Doctor, stern yet likeable, even as she insists on massacring the Zygon rebels. Drone pilot Lisa (Jill Winternitz) is only a one-scene role, but Winternitz is good at portraying Lisa's anguish and indecision as she decides not to fire a missile at beings who might or might not be her family.

Johnny Hitchley (Todd Kramer) and his mother (Karen Mann) have only one scene in the entire two-parter, but it's a memorable one because it's so powerful, thanks to their excellent performances. Mann, in particular, makes a huge impression as Hitchley's loving, nervous, frightened, resigned, homicidal mother. (Her best lines: "Don't kill me because I can't remember!" and her knife-twisting "You're going to kill me. ... You are! You're going to kill me. I love you. I forgive you, and I love you.") The audience is practically screaming at Hitchley, right along with Walsh, to ignore her and gun the lot of them down (yikes, we're a violent audience, aren't we?), and to be quite frank, he seems utterly idiotic to agree to follow them inside. I find it hard to believe that he can ignore the fact that she fails every single memory test. (And why? if Zygons can scan your memory to duplicate your loved ones, then she should know the answers to these questions, right?) But at the same time, it's also a rather sweet, non-cynical approach, acknowledging that sometimes a son's love for his mother is just too powerful to yield to logic. Hitchley's conflicted emotions are practically palpable, thanks to Kramer's sympathetic performance, and it's impossible to blame him for not being willing to put a bullet in his mother's head. Cynics might point out that it's practically propoganda for the Cybermen's "emotions are weaknesses" stance, although like the story's subtextual missteps in its handling of the refugee allegory, I'm sure it wasn't intended as such.

Gretchen Egolf is excellent as the frightened, jittery sheriff Norlander. I really enjoyed all of her very naturalistic line deliveries, especially "and suddenly, it turned into a... a reptile." and the way she drops her cap after "There isn't any backup, is there?"

I love that the Zygon High Command have named themselves Jemima (Cleopatra Dickens) and Claudette (Sasha Dickens)! The girls have mastered that faintly creepy child stare which they level at the Doctor, and their sychronized movements are slightly eerie too. Then they turn out to be the good guys! It's a nice twist, and the Dickenses give good performances on their few lines. So does Abhishek Singh, who's convincingly distraught as poor Sandeep. His parents (Samila Kularatne and an actor who's not credited anywhere I've looked) are chillingly soulless as malevolent Zygon duplicates, especially the dead-eyed stare Kularatne gives Clara.

Etoine (Nicholas Asbury) is a much-needed character in the story, as he alone becomes the face of the peaceful Zygons who genuinely want nothing more than a normal life coexisting with humanity. Aside from Etoine, every Zygon that the Doctor meets wants to kill him — he has no Zygon allies whatsoever, except for possibly Osgood — so Etoine provides some critical balance when all the other Zygons are portrayed as evil. Otherwise, the story's insistence that really, most Zygons are good, would have started to seem like nothing but lip service. Etoine provides a nice, if brief, glimpse at what ordinary life is like for Zygons on Earth, owning flats and going to the shops just like anyone would. Sadly, his story arc is tragic, as Bonnie rips away his disguise in order to provoke panic, which drives him to such desperation that he commits suicide. But in terms of storytelling, it's a wise decision, because it helps us empathize more deeply with the Zygons' plight.

Daniel Nettheim, yet another first-time Doctor Who director, adds some nice visual flourishes to the episode. I loved the shot of the camera floating through the TARDIS console room, the scenes at the beautiful (and convincingly Central-Asian) church with its tall steps, the shots of the Doctor and Osgood walking up the path from the beach, and my favorite, the gorgeous shot of Clara standing on the hillside, silhouetted against the sea, as her missile closes in on the plane. Like the plot, Nettheim too avoids some pitfalls that I thought for certain he was heading straight towards, like the scene of Clara brushing her teeth, which to my surprise did not include a shock moment when she closes her bathroom mirror. Hooray!

The incidental music this week is perfectly fine, if unremarkable. The nicer moments — like the creepy theme as the Zygon stalks into the police station after Osgood, or the music as Bonnie considers backing down from the Osgood Box — are balanced out by moments like the Doctor's confrontation with Jemima and Claudette, in which the comedy music seems to be setting us up for a punchline in which the two little blonde girls really are just two little blonde girls. (Thankfully, the episode doesn't actually go in that direction!)

Along with the designs of all the new Zygon technology, I loved the pink goop dribbling out of the elevator panel, and Clara's icky black dream-toothpaste. The Zygon costumes look great — possibly even improved over their appearance in The Day of the Doctor, unless they just reused the same costumes, in which case I retract my comment! I love the way the actors arch their backs and puff themselves up to indicate that the Zygon is about to naturalize. I assume the shots of the Turmezistan and New Mexico landscapes must have also involved the effects team, too, although if so, they're so seamless that they made me wonder if they were filmed on location, especially in the case of the New Mexico scenes (which, I have now learned, were apparently filmed on the Canary Island of Fuerteventura. A very clever substitution!).

Sooo I bent my rule a little bit. It's not every day that you get a Doctor Who birthday story — although I was forgetting I just had one last year — and I was eager to make sure that I did actually get to view The Zygon Invasion on or before my birthday; otherwise it would feel like I missed a rare opportunity to enjoy my birthday in the middle of new Who. However, out of a concern for plot details that might influence my previous review, I've always made myself wait to watch a new episode until I finished my final draft. And it was just looking impossible for me to finish my review of The Girl Who Died / The Woman Who Lived in time. At dinner that night, I was lamenting my reviewing speed to Gray, and he very gently suggested, "Well, we could just watch it...?" and suddenly I thought, yes! We certainly could! If you can't bend the rules for your birthday, when can you bend them? Besides, The Girl Who Died wouldn't have affected my review of Under the Lake at all, so let's risk it! Which led to us watching The Zygon Invasion actually on my birthday, which was a lot of fun, and I don't regret my decision one iota.

Minor points:

• I know it's silly, but I much preferred the original titles! Invasion of the Zygons and Inversion of the Zygons somehow had a much nicer mouth-feel, don't you think?

• Okay Moffat, what's with the stupid fairy-tale "previously on"? Besides being cheesy, the captions are totally superfluous. You don't need to tell us that there were two Osgoods, because we can see them perfectly well. Even worse, after the title "One peace treaty", the eleventh Doctor plainly explains to us that "then you're going to negotiate the most perfect treaty of all time"!

• Ucch. Annoying dialogue. In fact, no, although I have indeed been paying very good attention, there is absolutely no reason why I should have guessed this. I can only assume they're referring to the fact that, like the duplicate Osgoods, there are duplicate Osgood Boxes, but nothing they've said so far even hints at this answer.

  Osgood 7: "That's why the Doctor left us this."
  Osgood 4: "He called it the Osgood Box."
  Osgood 7: "If you've been paying attention, you'll be able to guess why."

• Aside from the Zygons and Osgood's taste in clothing, this week's blasts from the past include a lovely portrait of the first Doctor in the UNIT safe house (Gray spotted it well before I did!), Kate's declaration that she killed a Zygon with "five rounds rapid!" (I liked it; Gray groaned loudly), and — a more recent reference! — apparently a Mire helmet inside the Black Archive? Best of all are the references to Harry Sullivan, who was present during the first Zygon adventure. Kate drops hints about him twice ("There was an attempted Zygon invasion before. The seventies, eighties. One of our staff was a naval surgeon, worked at Portland Down on the captured Zygons. Developed Z67. It's a nerve gas, unravels their DNA. Basically turns them inside-out." and "The Z67, Sullivan's Gas, the gas the kills the Zygons, you took it.") as does, even more obliquely, the Doctor ("One of those buttons will destroy the Zygons, release the imbecile's gas." — poor Harry, he still can't escape that unfair nickname!).

• How has Clara managed to miss 127 calls from the Doctor?! Did she leave her phone in her satchel all day? (Maybe she's not allowed to check it during the schoolday? But surely between classes should be fine. What if there were an emergency? Anyway, she took UNIT's call during class in The Magician's Apprentice.)

• "I can't find my mummy and daddy," sniffles Sandeep. So Clara very kindly offers, "Well, why don't you wait here, and I can go see if I can find them." And where does she decide to look for his parents? In Sandeep's flat. What, does she think he hasn't looked there already?! Or that his mummy and daddy are playing a really successful game of hide and seek?

• First clue that Clara is a Zygon: when the Doctor answers her call, she says "Did you just call yourself 'Doctor Disco'?" before he even has a chance to say "hello"! (Or just possibly this is one of those annoying TV shortcuts, akin to people hanging up without saying goodbye.)

• The Doctor claims that "both of" the Osgoods were Zygons, because "they would've maintained a live link. They were both Zygon and human at the same time." Soooo being in active telepathic communication with a Zygon turns you part-Zygon yourself? That's ludicrous. I can believe the Osgoods didn't know which was Zygon and which was human, at least at first, but one quick round of "let's disguise ourselves as that squirrel" would've revealed the truth quickly enough.

• How come the Zygon rebels have their own control polyp?

• Given the immigration allegory, do you suppose it's a coincidence that when the Zygons shift back to their true selves, they "naturalize"?

• When Kate first mentions Sullivan's Gas, does she really refer to it as "zee-67"? Why not "zed"? Is it a military thing, like oh-nine-hundred hours?

• I was skeptical, on first viewing, that Clara and Jac would happen by at exactly the right time to see Sandeep's parents bundling him into the lift, but now I'm sure Bonnie arranged the performance.

• Again I must ask, what happened to UNIT's blue berets? I miss them.

• I kept thinking to myself how much I love the shots of tumbleweeds blowing across the New Mexico streets! It wasn't until after my third viewing, while I was brushing my teeth one day, that it suddenly hit me they might not be tumbleweeds...

• Do we say "advance bookings" in the USA...? I'm skeptical ("advance reservations" feels more natural to me) but I don't trust my skepticism, and a Google search is not helping...

• Ummmmmmmmmmm, how do the Zygon duplicates in the lift just disappear? Tell me they haven't developed teleportation abilities to go along with their new telepathy!

• Neat, this village in "Turmezistan" evidently speaks a Turkic language: "our village welcomes you" in Turkish is 'Köyümüz sizi karşılıyor' which looks a lot like what's on the sign (Kandimızda sizı alsışlayır). Google Translate doesn't recognize it, so it might be a made-up language, but it could also be a lesser-spoken one. Inquiring minds want to know! Either way, I really appreciate that level of attention to detail. (Ahh — the Turmezistan scenes were written for Azerbaijan, and the switch must have been a late one, because DWM 492 still refers to "such diverse locales as ... Azerbaijan." So it's quite likely that this sign is in Azeri, which is indeed a Turkic language whose alphabet includes all those letters. (It additionally includes the letters Ə, X and Q, but unfortunately we don't see any of those on the sign to confirm my hypothesis!)

• As much as I love the scene between Hitchley and his mom — after all, with hindsight, it could really have been his mother, since Bonnie was aware that UNIT was planning to attack the village, and could conceivably have taken the troops' families hostage in the interim — I'm not sure why he doesn't ask for details of this supposed "proof" before following her inside, and I really don't understand why he takes all the troops inside with him, rather than scouting it out on his own and then reporting back once he's sure it's safe.

• How do the Zygons dispose of the soldiers and then disappear so quickly? The Doctor and Walsh appear to infiltrate the building within 10 seconds, by which time roughly 9 Zygons have already managed to cough up 8 soldier hairballs, file down into the tunnels, somehow reposition the carpet perfectly, and escape without a trace.

• Also: are we really supposed to believe that the Zygons have dug tunnels to the UK??? I know they like their underground lairs, but this is ridiculous. They'd need Tractator-level technology for that!

• How do the Doctor and Osgood manhandle that unconscious Zygon out of the tunnels, clear of the strike zone, and onto a plane? In the middle of a bombing run? Especially without it waking up before they've managed to restrain it?

• HA! A wonderful exchange!

  Osgood: "You used to wear question marks."
  Doctor: "Oh, I know, yes, I did."
  Osgood: "They were nice. Why don't you wear them any more?"
  Doctor: "Oh, I do. I've got question-mark underpants."
  Osgood: "Makes one wonder what the question is."

• Yeah, that's totally the method of a peaceful coexisting species. (At least it answered my potential objection about the Zygons being able to instantaneously take any form they like.)

  Doctor: "Zygons need to keep the original alive to refresh the bodyprint. If you were the Zygon, you'd have changed back within days of your sister's death."
  Osgood: "Those were the old rules, before Zygons could pluck loved ones from your memory and wear their faces. Zygons only need to keep the original alive if they need more information from them. If the interrogation is over, then the original can die."

• If Zygon!Clara really wanted to have the humans destroyed, why did she pull the caul off the pod containing Human!Clara? Did she really underestimate Jac's knowledge of Zygon duplicates? Or was it really only ever a trap for UNIT? (After all, she does seem to have further need of Clara...)

• I'm dying to learn Harness' backstory on why Bonnie the Zygon is called Bonnie. It's not quite "Broton", is it? (Personally, I far prefer the Doctor's hilarious nickname 'Zygella'!)

• Aren't you curious to know how the actual 6,500 residents of Truth or Consequences feel about the fact that they've all been massacred by Zygons?

• Norlander mentions that the trouble in T or C was caused by a "child" Zygon... but if the Zygons on Earth all came from the same hatching, shouldn't they all be the same age? (Or do Zygons mate at a very young age, and some have had children already?)

• Norlander also seems to blame the humans for the fact that the child was "left alone to learn these things for itself"... but why didn't the other Zygons in the community teach it? That's not the humans' fault!

• This is definitely one of the better cliffhangers of the revival, with Clara replaced by an evil Zygon duplicate, Kate apparently zapped into a frizzy tumbleweed, and a missile heading straight for the Doctor and Osgood's plane. Especially in the last case, it's difficult to see how they're going to escape the situation! And it's resolved nicely in the teaser, which neatly avoids a copout when the plane really does blow up, even though the Doctor's solution to the problem (parachuting out) is the most unoriginal option.

• Even though the method isn't the same (and couldn't possibly have been, since Clara's the only person there), I appreciate that Clara references the Doctor's dream check from Last Christmas.

• Bonnie's been in control of Clara's body for quite some time. So how come Clara's only just now becoming aware of what she's doing? What triggered her "awakening"?

• Interesting, I didn't realize that a housing estate with shops on the lower level could be considered a "shopping centre". Filing that away for future reference.

• Hilariously, Bonnie's attempt to start a panic results immediately in Etoine, face covered in red pustules, flailing in front of a group of teenage guys... who could not look less panicked if they tried. They're completely unfazed! (Perhaps they're Zygons too?)

• Sure! Makes total sense. Ha! (However, I really doubt that the Doctor carries around his own parachute among the contents of those voluminous pockets, so shouldn't Osgood be asking why UNIT has one on their plane?)

  Osgood: "Why do you have a Union Jack parachute?"
  Doctor: "I'm camouflaged."
  Osgood: "Camouflaged?"
  Doctor: "Yes, we're in Britain."

• BRILLIANT. I love that the writers aren't afraid to poke fun at themselves. (Or perhaps, that Harness isn't afraid to poke fun at Moffat. My respect for his writing is definitely climbing quite a lot higher after this week. ...then again, I've also just learned that Moffat co-wrote part two, sooooo...)

  Osgood: "Sonic specs? Isn't that a bit pointless, like a visual hearing aid?"

• Impressive, Clara is able to send the Doctor a text message completely blind, with no autocorrect errors at all. My phone suggests "In sake" or "On sewage" as possible alternatives. (It probably helps that her message is very short!)

• Why would Osgood think to herself "Hmm, in the event that I'm interrogated, where would be a good location to hide a fake clue that I can safely give up to the enemy? Oh, I know! The secure UNIT safe house! Nobody will mind if the Zygon terrorists find out where that is."

• As the Doctor glances over his shoulder at the pursuing Zygon policemen:

  Bonnie: "You're dead."
  Doctor: "Yes, well, I'm dead now, and I think I might be a bit more dead in a minute."

• Is it me, or is the dialogue taking a distinct turn for the better?

  Doctor: "You know I'm over 2,000 years old! I'm old enough to be your messiah!"

• If a Zygon can retain a bodyprint independently of the original, then how are Bonnie and Clara's heartbeats linked? (Aside from that minor objection, this is a very clever way for Bonnie to detect when Clara's lying!)

• What? This line makes negative sense! Unless Osgood is a vegetarian? Clearly she didn't grow up in North Carolina!

  Osgood: "It stinks. Smells like... barbecues."

• All right, so at this point I'm really starting to wonder if we're ever going to see Clara's first visit to the Black Archive?

• As shapeshifters, shouldn't the Zygons be able to sense others of their kind? How does Bonnie not realize that Kate isn't a Zygon?

• As much as I feel that Harness has helped rehabilitate his reputation with this story, I still had my moments of eye-rolling, and this was one of them. The Doctor has heard Kate is dead, and when she turns up offering to lead him to the Zygon base, he oh-so-casually comments "Well, how very convenient, because that's just exactly what we're looking for." In other words, he's not fooled for a second. But then Kate does indeed turn out to be a Zygon, and his reaction — "Oh, you cheeky little monkeys!" — is to be annoyed with himself for not having realized?! How did he not realize?!?

• Kate claims to have shot the two Zygons in "self-defense", but they weren't planning to kill the Doctor, or her. They were only going to take him to the Black Archive, where he wants to go anyway. How is that self-defense?

• LOLOL. Something about the unironic way in which this is written and edited just really hits my funny bone! Kate has just shot two Zygons when the Doctor asks her this:

  Doctor: "How did you survive?"
  Flashback: Kate shoots a Zygon!

  As if to say, 'how did you think?' I anticipate many future post-shootout scenes involving the Doctor asking "How did you open that tin can?" (flashback: Kate shoots the tin can!), "How did you shear that sheep?" (flashback: bullets whizz through the sheep's wool!), "How did you circumcise that infant boy?", etc.

• Nice to see the Black Archive again, with its bulletin board of the Doctor's companions intact!

• Another superb discussion about the hard truths of war:

  Doctor: "What is it that you actually want?"
  Bonnie: "War."
  Doctor: "Ahh, ahh right. And when this war is over, when, when you have a homeland free from humans, what do you think it's gonna be like? Do you know? Have you thought about it? Have you given it any consideration? Because you're very close to getting what you want. What's it gonna be like? Paint me a picture. Are you gonna live in houses? Tell people to go to work? Will there be holidays? Oh! Will there be music? Do you think people will be allowed to play violins? Who's gonna make the violins? Well? Oh, you don't actually know, do you? Because, like every other tantruming child in history, Bonnie, you don't actually know what you want. So let me ask you a question about this brave new world of yours. When you've killed all the bad guys, and when it's all perfect and just and fair, when you have finally got it exactly the way you want it, what are you gonna do with the people like you? The troublemakers. How are you gonna protect your glorious revolution from the next one?"

• La la la, quoting the whole script...

  Doctor: "I just want you to think! Do you know what thinking is? It's just a fancy word for changing your mind."

• Such a sweet thing to say, it nearly brought tears to my eyes.

  Doctor: "You're all the same, you screaming kids, you know that? 'Look at me, I'm unforgiveable', well, here's the unforeseeable. I forgive you, after all you've done. I forgive you."

• "I fought in a bigger war than you will ever know!" claims the Doctor. Uh... you mean the war that destroyed their home planet? Yeah, kinda think they might know about it already.

• The Doctor tells Kate, "You've said that the last 15 times." While I enjoy the joke, I have to wonder when exactly these 15 times have occurred? That's an awful lot of time to keep running back to Earth to defuse human/Zygon conflicts. For that matter, how have UNIT and the Zygon High Command forgotten about the last 15 rebel uprisings? And did the Doctor wipe the memory of the 15 other insurgent leaders, or, like Bonnie, are they also out there (ineffectively) policing the cease-fire?

• This is kind of a biggie: Bonnie agrees to back down from destroying humanity, but surely she still feels her complaints are valid? Nobody seems to be concerned about addressing them, and nobody has persuaded her that it's better for the Zygons to live in secrecy, as far as I can tell. So how does she wind up so completely (and abruptly) converting to UNIT's side?

• Thanks anyway, Osgood, for trying to get him to settle the controversy! I adore the way the Doctor misquotes Susan.

  Osgood: "What's it stand for?"
  Doctor: "What? You're kidding me! Surely you know that."
  Osgood: "Well, I've heard a couple of different versions."
  Doctor: "I made it up from the initials. It stands for Totally And Radically Driving In Space."

• Adorable delivery by Ingrid Oliver:

  Osgood 5: "Ice creams?"
  Osgood 7: "Yes! Ice creams."

It's difficult to address an issue in Doctor Who that's as topical and polarized as welcoming refugees, especially when the fictional refugees in question are traditionally considered to be "monsters", but despite a few missteps, The Zygon Invasion / The Zygon Inversion handles the topic with sensitivity and a nuanced portrayal. The story gets a little bit bogged down by its complicated backstory, but simplifying it might have led to the tale being told in a single hour, and I do really appreciate the depth of narrative that a two-parter affords, especially for a multilayered plot like this. Like the other stories so far this season, I doubt this will ever be one of my favorites, but even though the script is far from watertight, it's a pretty solid, interesting tale that gets good mileage out of its setting and monsters. (Zygons yayyyyy! Come back soon, please!) I'm happy to see that the quality of these two-parters continues to remain high!