British submarine commander Sturm (Laughton), who's stationed on the North African coast, is insanely jealous of his bored wife Diana (Bankhead). When she's rescued from a mob by Lt. Sempter (Cooper), the two spend the night together and Sturm discovers her infidelity. Finally cracking, Sturm traps Diana aboard the sub with his crew before sinking the vessel but Diana isn't about to die. Laughton's Hollywood debut piles on the ham and cheese although his performance was praised at the time.