Somewhere in the Gulf of Mexico, an Asian Flag container ship sails into mysterious, fog-shrouded waters. After observing strange, shadowy faces floating on the ocean's surface, the foreign crewmembers believe the vessel is stalked by devils. The ship inexplicably sinks, leaving one sole survivor to recount his astonishing tale. Kenneth Swain is a disgraced and dishonored attorney, desperately struggling not to succumb to financial ruin. While cleaning out his office files he discovers records of another peculiar shipping disaster at an unidentified location in the Gulf. It was a tragedy that left five survivors either suicidal or confined to mental institutions. The report specifies that the steamship family's assets lie with the tanker at the bottom of the ocean floor in the form of precious gems and jewels. Kenneth hastily believes he has happened upon his deliverance from financial ruination. Incredibly, upon further examination, Kenneth finds unnerving testimony describing a demonic apparition that appeared before the disaster. Karen West is one of the survivors from the ill-fated tanker disaster. She is a beautiful young woman who is trying to pick up the pieces of her life after losing her lover in the same tragedy. She maintains a psychic relationship with her ghostly lover with the help of a mystical talisman. Karen is also psychologically harassed by the same demonic entity that was responsible for her heartbreak. Kenneth visits an unsettling state mental health center trying to persuade a mentally disturbed and tormented steamship owner to relinquish the location of the sunken ship. After this ploy fails the desperate attorney heads to Key West and hires a suspect salvage team. Along the way he establishes an unwilling relationship with a dubious ex-shipping agent, and the beautiful yet burdened psychic. The trio is then followed by the dangerously deranged mental patient who escapes and is led by the demon's terrifying imp to pursue them. The salvage tug and its crew sail into the mysterious seas searching for the wrecked hulk. Ghostly apparitions and psychic contact haunt the venture throughout its search and underwater recovery. Disaster and misfortune plague the crew during the salvage operation. After recovering the treasure and realizing their dreams of wealth, a powerful hurricane prevents their return to Key West. The tempest reroutes the besieged tug, beaching the vessel on a remote part of western Hispaniola. Here the foul entity and its malevolent imp fatally manifest themselves into human form.