Parts: 2 (45-minute)
Writers: Jamie Mathieson and Steven Moffat (part 1), Catherine Tregenna (part 2)
Airdates: 17 — 24 October 2015
Production Code: n/a

Doctor: twelfth
Companion: Clara

Creature Feature: the Mire, Delta Leonians

Story: A quick stop on Earth turns into an extended visit when the Doctor and Clara are captured by Vikings moments after stepping out of the TARDIS. Days later, they arrive in the Viking village, where the Doctor's attempts to awe the locals are quickly outclassed when the floating head of Odin appears in the sky. Odin bellows to the villagers that he wants their strongest warriors to join him in Valhalla... at which point the village is occupied by a dozen alien soldiers, who kidnap them — along with Clara and Ashildr, a local girl — and disappear.

The Doctor is frantic to recover Clara, but perhaps not quite as defeatist as when he learns that the villagers have somewhat accidentally declared war on the aliens, who now plan to descend in 24 hours and raze the village to the ground. In one short day, the Doctor must turn the fishermen and craftsmen into skilled fighters... but his plan has consequences that even he does not anticipate.