American Judge Crowdy Lobbett has suffered several attempts on his life and has decided to leave the United States and travel to England in the hope of finding a safe haven. The Lobbett family meet Campion on board their transatlantic liner, and the Judge's son Marlowe asks him to help with their problems. Campion takes the Lobbetts to the village of Mystery Mile, where he has friends, but the Simister gang is on the Judge's trail and he soon disappears, leaving Campion and the Lobbetts with a kidnapping to solve in a hurry.

Judge Lobbett mysteriously disappears, Biddy Pagett is kidnapped and Lugg tries to warn Campion off the Simister mob investigation, but he refuses to give in.