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
Paradise Towers headed to the top of the building, and are captured by a party of Blue Kangs. Before the pair are freed the Kangs reveal to Mel that Pex survived by fleeing from the war. The Doctor finds the Great Architect is named Kroagnon, and is reunited with the Red Kangs. They explain that Kangs and Caretakers have been disappearing in ever greater numbers. While the Doctor is being interrogated, the Caretakers track him down to the Red Kang headquarters and attempt to break down the door. Elsewhere Mel has visited Tilda and Tabby again and soon finds herself under threat