Below

A U.S. Navy submarine crew in 1943 rescues survivors from a sunken British ship and is soon hunted by a German destroyer while mysterious deaths and supernatural events erupt aboard.

Below follows Lieutenant Brice, acting commander of the USS Tiger Shark, as the boat patrols the Atlantic in August 1943. Ordered to recover people spotted by a British Catalina, the crew hauls aboard British nurse Claire Paige and two men from the torpedoed hospital ship Fort James. One survivor insists a German U-boat was on the surface moments before the hit. A pursuing destroyer forces the Tiger Shark through repeated depth-charge attacks that damage the hull and fray nerves. Brice later learns the wounded man is German prisoner Bernhard Schillings; convinced the prisoner has been making noise to give away their position, Brice confronts him, and when Schillings seizes a scalpel in panic Brice shoots him dead.

Brice then tells Paige that the Tiger Shark recently sank a German submarine tender and that previous skipper Lieutenant Commander Winters died after the boat surfaced to confirm the kill. As the patrol continues, unexplained malfunctions, vanishing crewmen, and apparitions begin to claim lives inside the cramped compartments. Paige and the remaining officers piece together contradictions in the official account of Winters’s death while the destroyer overhead keeps them submerged and running out of air and options. Guilt, mechanical failure, and what may be a haunting close in together, forcing Brice, Paige, and the survivors to decide whether the greatest threat is the enemy above or something already inside the Tiger Shark.