After a period of drinking and flirting in Shanghai dives, some American sailors are called back to their submarine, which is under the command of Bridewell. Their craft is hit by a freighter and sinks to the bottom of the China Sea, provoking various emotional reactions from the crew. Burke, a British naval officer, brings a ship to their aid, is recognized as a disgraced officer by one of the crew, Weymouth, but remains behind to rescue the last /merican through a torpedo tube, thus protecting the woman he loves and establishing his bravery.