It was nominated for an Academy Award for Best Visual Effects.
The American submarine Grayfish, under Lieutenant Commander/Commander Barney Doyle (Glenn Ford), searches for the Shinaru, one of the Japanese aircraft carriers that led the attack on Pearl Harbor. Doyle receives word that the target has an escort, including a transport ship carrying his wife and child, who were captured in the Philippines.
As luck would have it, Grayfish finds the ships. Doyle's second in command, Lieutenant/Lieutenant Commander Archer Sloan (Ernest Borgnine) tries to talk his friend out of risking the lives of his family, but Doyle proceeds with the attack. To their horror, their torpedoes sink the transport. The Japanese make no attempt to rescue the survivors, hoping to lure the sub to the surface. Doyle is forced to leave the prisoners to drown.
Doyle manages to follow the Shinaru into Tokyo Bay itself and tries again to sink his nemesis, but fails and barely escapes from Japanese destroyers. The Grayfish then returns to Pearl Harbor. There, Vice Admiral Setton (Philip Ober) wants to promote Doyle to a desk job, but the anguished man begs for and gets one last chance at the Shinaru. Sloan turns down a command of his own to accompany him.
Doyle is assigned a quiet, out-of-the-way patrol area off the Alaskan coast, but fortune is with him. He encounters the Shinaru once more. The sub sustains some damage from a collision and has to launch its attack using sonar alone. After the torpedoes are away, the sub is sent to the bottom by the Shinaru's escort. Fortunately, the crewmen are able to exit and use Momsen lungs to reach the surface, where they are rescued by a sister sub. When they are brought aboard, they are told that they have sunk the Shinaru.