Crash Dive

Lieutenant Ward Stewart commands a PT boat and sinks a German U-boat, saving a lifeboat full of survivors. The rescue demonstrates his prowess as an underwater warrior and earns him a reputation within the Navy. Upon returning to port, he is reassigned to the submarine USS Corsair due to a shortage of trained submarine officers.

Back at the submarine base in New London, Ward meets his new captain, Dewey Connors. The meeting is tense, reflecting Stewart's reluctance toward the submarine service and Connors's command style. The uneasy dynamic foreshadows later conflicts and competition.

Stewart arranges a weekend pass before Corsair sails. Connors takes a few hours off to meet his girlfriend, Jean Hewlett, a New London schoolteacher. Hewlett has to step in for an ill teacher to chaperone honor students, and Connors declines to accompany her.

Stewart travels to Washington, D.C. on the same train as Hewlett, and the two meet again. Despite her initial resistance, he begins to romance her, setting up a complicated dynamic with Connors looming in the background.

Connors and Hewlett dine together, and she suggests marriage. Connors reveals he plans to marry only after a promotion to commander to support her financially. Stewart's fixation on PT boats continues to irritate Connors, though their professional relationship endures.

Stewart's zeal for PT boats irks Connors, but their professional bond grows stronger after they jointly engage a Nazi Q-ship. The successful action demonstrates their capability as a team and begins to ease personal frictions.

Connors is wounded during the operation, and Stewart takes command of the Corsair to sink the Q-ship. The mission showcases Stewart's leadership under pressure and deepens the fragile partnership between the two submariners.

Corsair returns to base in New London, and Stewart continues to woo Hewlett. He arranges a dinner that unexpectedly turns out to be at his Uncle's home, adding a personal twist to the couple's evolving relationship.

Connors returns from a Washington briefing with a promotion, and Stewart discovers Connors is also in love with Jean and about to propose. The two men confront the love triangle, and their shared professional duties threaten to complicate the war effort.

The DC briefing reveals a secret island supply base connected to the earlier Q-ship and other German raiders. The Corsair sails to locate and destroy it, while Jean Hewlett watches from offshore, anxious about the mission.

The search results in sighting a German coastal tanker. Rather than sinking it immediately, Connors and his crew shadow the tanker through the harbor's anti-submarine nets, preparing for a decisive strike and the harbor raid to follow.

A landing party of eight, led by Stewart, is put ashore to destroy as many German munitions as possible in 30 minutes. Meanwhile, the Corsair sinks other ships in the harbor, making the raid a significant tactical success.

Chief Mac MacDonnell reveals a concealed heart condition and sacrifices himself to cover Stewart and Jones's escape. Stewart and Jones swim back to the boat, and Connors submerges the Corsair and heads out to sea, despite his wounds.

After the Corsair returns to New London, Stewart and Jean are married, bringing a personal resolution to the intertwining professional and romantic tensions that have driven the story.