Placing his life entirely in their hands, the Doctor agrees to search for the recipient of the fourth envelope - just who is Canton Everett Delaware the Third? And what is the relevance of their only other clue: 'Space 1969'? Their quest lands them - quite literally - in the Oval Office, where they are enlisted by President Nixon himself to assist enigmatic former-FBI agent Canton, in saving a terrified little girl from a mysterious spaceman.

The Doctor is locked in the perfect prison. Amy, Rory and River Song are being hunted down across America by the FBI. With the help of new friend and FBI-insider, Canton Everett Delaware the Third, our heroes are reunited to share their discoveries, if not their memories. For the world is occupied by an alien force who control humanity through post-hypnotic suggestion and no one can be trusted. Aided by President Nixon and Neil Armstrong's foot, the Doctor must mount a revolution to drive out the enemy and rescue the missing little girl. No-one knows why they took her. Or why they have kidnapped Amy Pond...