Gangster Lee Lother (Sidney Blackmer) is shot and killed during an ocean liner cruise, and we're introduced in flashback to the interwoven stories and characters of the suspects: con-man and jewel-thief Jimmy Brett and his accomplice, a wife who bids goodbye to her husband without realizing he'll stowaway to spy on her, the star of the ship's entertainment revue and her brother with gambling debts, and the Inspector who interrupts his vacation to solve the case.