The Doctor, Amy Pond and Rory Williams arrive late for dinner at the home of Lord Cranarch, Repton Abbey. The downstairs servants and all the dinner guests have been taken over by a gang of invading reptilian aliens. The aliens (led by a Lord Ryzt) are collecting the thoughts and memories of the household, using devices called dullifiers. The bodies are being kept alive, linked to a stasis generator to store the memories, which are being fed back to the aliens. Central to their plans for Earth's conquest are the national defence plans known to Lord Cranarch, who held a position high in British intelligence.