Ed Harwood, a wisecracking private investigator from New York, discovers a crime at a hotel in Nice during a carnival. The unraveling of the mystery which lies behind will lead him and Caryl Fenton, a female insurance agent, who will become his companion, first to Paris, then to London, later through the English countryside and finally to Southampton, in search of a criminal train wrecker.

• Gaumont-British Picture Corporation
• Edmund Lowe
• Constance Cummings
• Thomy Bourdelle
• Henry Oscar
• Felix Aylmer
• O.B. Clarence
• Mark Lester
• Allan Jeayes