The story unfolds around two close friends and Navy sailors, Jack and Bob, who share a tight bond strengthened by their adventurous and daring submarine missions. Jack, known for his brashness and leadership, often takes the more daring risks, while Bob is his loyal and dependable counterpart. Their camaraderie is challenged when they meet Nellie, an alluring nightclub singer, during shore leave. Jack becomes instantly smitten with Nellie, rapidly falling in love, while Bob observes the burgeoning romance with quiet admiration and growing concern. As Jack devotes more time to his new love interest, tension starts brewing between the trio, testing their friendships and emotional entanglements.

Their personal lives are abruptly overshadowed by duty when a catastrophic accident occurs on their submarine during a routine mission. Stranded and trapped at the bottom of the ocean, the crew must rely on Jack's leadership skills and Bob's steady calm under pressure to navigate the treacherous situation. The looming danger inside the submarine forces Jack and Bob to confront their personal tensions, particularly surrounding Nellie, as they fight to survive and uphold their duties as sailors. Facing mortal peril, each man must weigh personal desires against collective responsibility and friendship loyalty as they push towards a precarious rescue mission that could determine their fates at sea.