As commander of the British warship H.M.S. Defiant, the humane Crawford (Guinness) strives to maintain order throughout the ship against the ceaseless brutality of sadistic first mate Scott-Padget (Dirk Bogarde).

After Crawford is injured in a fiery battle with a French treasure ship, angry seamen Vizard (Anthony Quayle) leads the crew to mutiny when Scott-Padget takes over. Now with Vizard in command, Crawford persuades him to join the British fleet to help fight against France's planned invasion of England in hopes for a mutiny pardon. But when a vengeful sailor murders Scott-Padget, the Defiant crew must decide between saving their country or their own lives.