Based on Agatha Christie's "The Secret Adversary," a young couple looking for adventure become involved in the mystery of a missing woman and an espionage ring.

An unknown gang has again broken into a van containing money from the European bank. Banker Sam Hamilton decides to use an armoured car for the next money transport. He hires racing driver Charly Allan as the driver. Allan is invited to Hamilton's house for a party. During a dance with the banker's daughter Bessy he is attacked by bandits, pushed to the ground and Bessy is kidnapped.