Parts: 2 (1 x 45-minute, 1 x 65-minute)
Writer: Russell T Davies
Airdate: 28 June - 05 July 2008
Production Code: n/a

Doctor: tenth
Companion: Donna, Rose, Jack, Mickey, Martha, Sarah, K-9 mark IV

Megalomaniac of the Week: Davros
Creature Feature: Daleks
Special Guests: UNIT, Jackie

Story: Alarmed by a warning that the universe is in danger, the Doctor and Donna return to the Earth to find nothing but a perfectly normal day. But after they go back inside the TARDIS, the residents of the planet feel a strange shaking... and when the Doctor again prepares to set foot on the Earth, he finds nothing outside the TARDIS doors except empty space. The Earth has been taken by someone... but by whom, and for what purpose? And where has it gone?

While the Doctor and Donna try to find the answers to those questions, his companions around the globe are suffering from the aftereffects of the planet's shift. Martha is in New York with UNIT, Jack and his Torchwood coworkers are beneath the bay in Cardiff, and Sarah is at home with Luke in Ealing. Along with the rest of the planet, all of them are shocked to look up and see not familiar stars, but an array of planets in the sky. The shock only gets worse when an array of spaceships is spotted approaching the Earth, and they send a message consisting of only one word: "Exterminate."