In 1942, journalist Manning (Loder) arrives at an English air base to learn about the Free French who are fighting the Germans. Manning's interest focuses on Jean Matrac (Bogart), a gunner, and Captain Freycinet (Rains) describes Matrac's story: Two years earlier, just before the defeat of France by the Germans, five convicts, led by Matrac, escaped from Devil's Island and are found adrift in a small canoe in the Caribbean Sea. When they find out about the situation of the war, they decide to join the forces against the Nazis.
This film features examples of:
- Flashback: A reporter comes to an air base to interview a Free French officer, who starts telling the story of one of his men. Flashback to the man being recovered at sea by a ship along with four others. It is revealed that they are escaped prisoners. Flashback to them planning to escape in order to join the fight against the Germans...
- Frame-Up: It is revealed that before the war, Matrac was a crusading journalist opposed to the Munich Pact, and was framed for murder to shut him up.
- Great Escape: The group of convicts led by Matrac escape Devil's Island by raft.