Adapted from Richard Sale's novel, men escape from an island prison colony; most die along the way as a mysterious man guides them.
In a Guianas prison colony Verne (Clark Gable) is let out of solitary after five escape attempts. Verne works on the wharf and grabs the ankle of Julie (Joan Crawford), saying he will meet her. Verne escapes as Cambreau (Ian Hunter) takes his place. Verne goes to Julie's room, and she kisses him; but she turns him in. Grideau (Frederick Worlock) expels her and gives her twelve hours, paying off Monsieur Pig (Peter Lorre). In prison Cambreau gives Moll (Albert Dekker) money so he and Verne can go with him. Pig offers to take Julie to the mainland, but she prefers to go with Marfeau (Bernard Nedell). Men working escape, and Verne breaks out. Cambreau leads Moll and Hessler (Paul Lukas) in the jungle. At a mining camp Cambreau's voice keeps Julie from stabbing Marfeau. Flaubert (J. Edward Bromberg) hits religious Telez (Eduardo Ciannelli) with a rock and takes his bread. Verne comes in and demands food from Marfeau and Julie. Marfeau attacks but is knocked out by Julie and Verne, who leave together. Verne reads love poetry from the Bible to Julie.
Moll, Cambreau, and Hessler arrive at the beach and are joined by Flaubert and Duford (John Arledge). Telez arrives with a bad leg, and Cambreau helps him. Cambreau comforts Telez as he dies. Julie and Verne collapse on the beach. Moll has a boat and fights Verne, who wins and takes charge. They sail with Verne steering and kissing Julie. After five days they are becalmed. Duford asks for water, but Flaubert throws the keg overboard. Flaubert jumps in to get it but is killed by a shark. Moll socks Duford to keep him from going in, and Cambreau says Duford is dead. Cambreau says the keg may have salt water in it; so they draw lots. Verne loses, but Moll drinks and says it is no good. Julie also confesses to Cambreau, who says she will live. Cambreau says they are near the mainland, and they sneak in at night.
In the house of a fisherman (Victor Varconi) they get water and food. Cambreau pays him to use his boat. Hessler shaved and goes out to find a woman. Cambreau follows to watch him. Verne shaves and asks Julie to marry him, promising to become honest. Julie says she hates him. Grideau finds the boat with dead Moll and Duford. On the street Pig sees Julie and says Grideau thinks Verne is dead. Julie tells Pig she will go with him if Verne can get away. Julie warns Verne about Grideau. Verne leaves but comes back after Pig comes in. Verne suspects Pig squealed and hits him. Julie holds a gun to keep Verne from strangling Pig. Verne takes the gun and makes her leave with Pig. Cambreau tells Verne that Julie is protecting him. Verne and Cambreau make the fisherman take them on his boat in a storm. Cambreau provokes Verne into knocking him into the sea. Verne tells Cambreau to pray to him and dives in to save him. Verne comes back to Julie and Grideau and plans to wait for her.
Spiritually aware Cambreau helps various characters
to know themselves better and guides them. He even gets arrogant
Verne to reform by having him rescue him.