 Aboard the U.S. submarine S13 in the China seas, Chief Torpedoman Burke goes about his duties. In actuality, he is Quartermaine, the infamous former commander of the British ship Royal Scot, which was sunk by Germans with a Field Marshal aboard. Quartermaine had told his sweetheart that the Field Marshal would be aboard, not knowing that she was an informant for the enemy. When the S13 sinks, Burke takes charge when the commander, Ensign Price, is unable to command. Burke must keep his mates alive long enough on the bottom of the sea for rescuers to arrive.