A supernatural thriller that plunges into the deep claustrophobia and sensory deprivation of the underwater world. The journey begins as the crew of the USS Tiger Shark, a World War II sub prowling the mid-Atlantic waters, heads for its homeport in Connecticut. At the end of a long and deadly mission, the crew is ordered to take on three surviviors of a torpedoed British hospital ship. To the shock of the men, the refugees include a female nurse, who reminds them of the age-old fable that a woman on a submarine brings bad luck. Indeed, bad luck ensues, as the sub finds itself unable to surface, putting everyone at risk of oxygen deprivation. Making matters worse, the alluring new passenger begins asking probing questions about a recent death aboard the sub. Soon, the crew finds itself battling not just the Allies, but for their own sanity as apparitions, disturbing noises and spontaneous accidents begin to plague the journey home.