Fact1: American oil tanker captained by Capt. Steve Jarvis is sunk in North Atlantic Ocean by German U-boat, Fact2: merchant seamen including Northern Star survivors spend time At union hall waiting to be assigned to new ship, Fact3: Pulaski When pressed by reveals fear of dying at sea other seaman, Fact4: sea is carrying vital war supplies to Soviet port of Murmansk, Fact5: Nazi sub not get by daylight because of ship 's 5-inch guns
Output: An American oil tanker, the SS Northern Star, captained by Capt. Steve Jarvis Raymond Massey, is sunk in the North Atlantic Ocean by a German Uboat. Along with the First Officer, his friend Joe Rossi Humphrey Bogart, they make it to a lifeboat loaded with other crewmen. When the UBoat crew starts filming their plight, they respond with rude gestures, and their lifeboat is rammed by the sub. The survivors swim to a raft and are finally rescued after 11 days adrift. During their brief liberty, Steve spends time with his wife Sarah Ruth Gordon, while Joe meets and marries singer Pearl ONeill Julie Bishop. At the union hall, merchant seamen, including the Northern Star survivors, spend their time waiting to be assigned to a new ship. Over a round of poker, Johnnie Pulaski Dane Clark jokes about getting a shore job. When pressed by other seaman, Pulaski reveals his fear of dying at sea. The others shame him into signing along with them on another ship. Another sailor, Alfred Boats OHara Alan Hale, Sr., is tracked down by his wife, who has apparently not seen him since he was rescued. She angrily serves him with a divorce summons. OHara, knowing he is headed back to sea, gleefully tears it up, saying Them Liberty boats are sure well named. Then it is back to sea aboard one of the new Liberty ships, SS Seawitch, on a convoy carrying vital war supplies to the Soviet port of Murmansk. This transport ship is armed with a 5inch gun and antiaircraft guns, and a Navy Armed Guard force joins Seawitch to operate them. They also instruct some of the crew in groundtoair gunnery, to replace them in case they ever become casualties. In Halifax the captains are instructed on how to sail in the convoy. En route, Convoy 211 is attacked by a wolfpack, a group of German UBoats that coordinate their attacks on Allied convoys. There are losses on both sides, and the convoy commander is forced to order his ships to temporarily scatter, to reform at a preset rendezvous point. A persistent UBoat chasing Seawitch means she must stay away from the convoy when it reforms. The Nazi sub cannot get close by daylight because of the ships 5inch guns, and during the night Seawitch eludes the Uboat by shutting down her power plant to prevent detection by Nazi sonar. Nearing land, the sub contacts the Luftwaffe, and the next day a pair of Heinkel He 59 seaplanes find Seawitch and attack with machine guns and bombs. Both aircraft are shot down, with one crashing into the Liberty ships bow. Several seamen are killed and Captain Jarvis is wounded; Joe Rossi takes command. Then the UBoat returns and torpedoes Seawitch. Rossi orders the crew to set deck fires and make smoke from the stack so it appears as if they are sinking. When the submarine surfaces to finish the job, Seawitch sails through its smoke screen and rams the UBoat, sinking it. As they get nearer to shore, a flight of Russian fighter aircraft appears and escorts Seawitch, with its valuable cargo intact, into Murmansk to a warm Russian welcome.