The Doctor is framed for causing the appearance of the dinosaurs.
The crew of the ship includes Mark, Adam and Ruth, minor British celebrities who have adopted new aliases and lives. They tell her they are en route to a New Earth where mankind can begin again, closer to nature. They left Earth three months earlier; the ship is one of a fleet carrying over two hundred people to a new life. Sarah is committed to the re-education program to enable her to think like them. The Doctor searches London in his new vehicle, the Whomobile. Under Moorgate Station he finds the base used by Whitaker and Butler, but is scared away when they use a pterodactyl to defend it. He returns with the Brigadier, but all signs of occupation have been removed. Operation Golden Age is revealed to be a broad conspiracy including Whitaker, Butler, Yates, Grover and Finch as its core coordinators. They have emptied London to let it to revert to a more natural state, after which the people on the spaceships — in reality in vast bunkers — will be allowed out to repopulate a clean and free planet. Whitaker also works out how to reverse time, so soon humanity, apart from their own chosen specimens, will never have existed.
Finch tries to frame the Doctor, who he knows will not support their plans. He brings the Brigadier to the Doctor, catching him in the act as a new time eddy starts up.