Paradise Towers two elderly residents ("rezzies") live. Tilda and Tabby explain that all the able-bodied men left the Towers to fight a war, leaving behind only children and the elderly. The only other man still loose in the Towers is Pex, a would-be hero, who appoints himself Mel's guardian. At the Caretaker control centre, the Doctor meets the Chief Caretaker, who greets him as the Great Architect, designer of Paradise Towers, and then promptly calls for him to be killed The Doctor cites an imaginary rule from the Caretakers' manual, confusing them enough to make his escape. Mel and Pex meanwhile have
The Invasion (Doctor Who) his niece Isobel. As the professor has gone missing working for International Electromatics, the Doctor and Jamie leave investigate its head office. After being caught investigating, they are brought to Tobias Vaughn, the company's Managing Director. He claims that Professor Watkins being at a delicate stage of his work and refusing to see anyone, though the Doctor notices unusual behavior and quickly becomes suspicious. Shortly after their meeting, the Doctor and Jamie are abducted by two strangers and taken to meet their commanding officer, Alastair Lethbridge-Stewart. Having been promoted to Brigadier after their encounter with the Great Intelligence, he reveals