A church official with a taste for mysteries gets mixed up in the real thing.

Donald Meadows, a young American studying architecture on a walking tour of England, is infatuated with pretty Hester Grantham, whom he meets in the cathedral at Broadminster. When he learns that she wants him to help her rob Guy Waller, a man who has cheated her father out of a valuable patent on one of his inventions, he thinks she is joking, but reluctantly agrees when she promises to go ahead anyway. The plan, which includes Collins, Waller's chauffeur, "Red," the bartender at the Red Lion Inn, and "Frenchy," a henchman they find in Limehouse, goes off perfectly until the Bishop of Broadminster and his sister Emily accidentally become involved. The bishop, who is devoted to detective novels, thrives on the adventure, as does his sister. The bishop finds and takes possession of the jewels and documents which the gang steals, then waits for them to come to his home to retrieve them. During a night of adventure and intrigue, the gang, Waller, and the bishop match wits until Donald and the bishop, with the help of Millie, Waller's wife, force Waller to give Hester money for her father's patent. Donald and Hester, having decided that they are in love, retire from the crime business, the other thieves are able to sneak away, and the bishop, realizing that his thirst for adventure has caused too much trouble, burns all of his detective stories.