Action in the North Atlantic

Steve Jarvis (Raymond Massey) and Joe Rossi (Humphrey Bogart) are the captain and executive officer of the SS Northern Star, an oil tanker. The ship is torpedoed and sunk by Germans in the north Atlantic Ocean. Their lifeboat is also destroyed by the Germans, which leaves them adrift on a flimsy life raft. They are rescued after eleven days and vow to avenge their ship. While waiting for a new ship to serve on, Steve reconnects with his wife, Sarah (Ruth Gordon), while Joe marries nightclub singer Pearl O'Neill (Julie Bishop). Soon the men are assigned to a ship called the SS Seawitch and are told that they will be part of an international convoy to bring supplies to Murmansk in the Soviet Union. The ship is equipped with anti-aircraft guns manned by Navy personnel. The convoy is attacked by a group of German submarines, one of which singles out the Seawitch. The ship heads out alone to lure the submarine away from the convoy. As the ship hides out at the edge of the Arctic Ocean, the submarine breaks off, but radios the Seawitch's location to German airplanes which launch a devastating attack. Steve is seriously wounded, and multiple crewmen are killed. Joe takes command and is determined to bring the ship into port successfully. Soon the submarine returns with the intention of finishing off the Seawitch. In a desperate fight, Joe employs any tactic he can to fend off the submarine and keep the Seawitch alive.