Thos. T Knapp, a low-class criminal of Campion's acquaintance, arrives with news of their enemies, and they all decamp to London to rescue Biddy, leaving Lobbett's daughter safe in Campion's flat. They break into the house of the fortune-teller, where Biddy is being cruelly interrogated, and after a fight and Campion's use of a smoke-bomb, escape, leaving the gang in disarray. Back at Campion's flat, they see a photo of the judge in a newspaper, and Campion reveals that he had arranged for the disappearance, and hidden the man on a nearby estate, following St. Swithin's advice. They go there, fetch the judge, and he, Giles and Campion decamp for Mystery Mile once more, where they find the household, including Mr Barber, drugged. They retrieve the judge's evidence—a book of stories from the Thousand and One Nights from his set—and Giles and the judge flee using the same path used to smuggle the judge away before, a boat from a beach near some dangerous "soft" – mud that works like quicksand. Campion sits in the hut and deciphers the clue—the art expert's name is Ali Barber. The man comes in, and reveals his secret role as Simister, head of a colossal criminal gang, inherited from his father. He tries to kill Campion with a syringe filled with acid, but Campion breaks through the floor of the hut and falls beneath it. Barber goes to retrieve the book, but is taken by the soft mud, dying horribly. Recuperating later, Campion's friend Stanislaus Oates tells him the secret of Swithin Cush's suicide – he was in fact not a parson at all, having taken the place of his brother who died young. The fortune-teller, a blackmailer working for Simister, knew this and threatened to reveal it. Biddy and Giles Paget plan to marry Marlowe and Isopel Lobbett, respectively, and to sell the valuable painting for a small fortune. Characters in "Mystery Mile" Magersfontein Lugg, Campion's servant, a beefy ex-crook Giles Paget, owner of the manor on Mystery Mile, a friend of Campion Biddy Paget, Giles' sister, whom Campion admires Addlepate, originally owned by Campion but now the Paget's dog Crowdy Lobbett, an American judge, scourge of gangsters Marlowe Lobbett, his handsome son Isopel Lobbett, his attractive daughter Swithin Cush, rector of Mystery Mile, a friend of the Pagets Ali Ferguson Barber, art collector and bore Thos. T Knapp, low-class London criminal, known