Subtitled "A Story of Submarine Service," sailors struggle to survive as air runs out in a submerged submarine until they are rescued.
This film has music and some singing and talking, but most of the dialog is conveyed in writing. In Shanghai sailors drink at the world's longest bar. An American woman sings "Tattooed Lady." Burke (Kenneth MacKenna) tells Costello (J. Farrell MacDonald) and others to get on board. Commander Weymouth (Charles K. Gerard) sees Burke and thinks it is Quartermain, whom he thought was dead. He had judged his late best friend guilty and exonerated his woman friend. The new Ensign Price (Frank Albertson) reports to the captain. Sailors are allowed to return to the ship drunk, because of the dangers they face; but bottles are confiscated or broken. Weymouth believes that Quartermain is aboard the S-13 submarine. After it collides with another ship in a storm, the S-13 sinks ninety feet as the engine room floods. The captain was washed away with the lookouts, putting Price in charge.
Burke says they can last a few hours if they are careful with the one tank of oxygen. A volunteer tries to get out but has to return, because the valves are jammed. Burke uses some of the oxygen. Men start to fight for more oxygen but are calmed down. The telegraph man keeps sending S-O-S, but there is no answer. Pollock (George LeGuere) panics and explodes a detonator. A ship on the surface signals. Pollock preaches the vengeance of God and is shot and killed by Price. Burke has a magazine with a picture of Quartermain's woman.
A British ship calls and is above them. They ask about Burke. Burke says water on the control board will cause chlorine gas. So they go to the torpedo room. Two divers in suits go down. Cobb regrets going after dames and says his wife was a good kid; he collapses. Divers find the hull. Men are quiet and hear the divers tapping. A message is sent to clear the port tube. Divers use an acetylene torch to clear the torpedo tube. Price stays behind to work the tube. The first man makes it to the surface and is picked up by a boat. One at a time men go into the tube and are picked up by boats. Finally Burke tells Price to go; but Price says the captain always stays with his ship. Burke tells him how he lost his ship, because he told his woman friend about having a field marshal on board. If he returns, Burke's woman friend would be condemned by Weymouth. Price refuses, but Burke knocks him out and puts him in the tube. Price is carried onto the ship. Weymouth asks Price about Quatermain; but Price says he knows he is Burke. In the final scene taps is played for Burke.
Not for the claustrophobic, this story explores the dangers and sacrifices of submarine sailors. Since one man has to die, Burke sacrifices himself for the woman he loves even though her spying cost lives.