Deep beneath the Atlantic Ocean, a team of American researchers and miners working for a corporation is on a deep-sea drilling mission to extract silver and other precious metals from the ocean floor. Led by geologist Steven Beck, the crew's routine operation takes a turn when they discover the wreck of a Soviet vessel named Leviathan. Eager to claim salvage rights, the team penetrates the shipwreck, finding a cargo that includes suspiciously sealed containers and the ship's log. Their curiosity leads to the discovery that the Soviet crew had succumbed under mysterious circumstances.

The discovery of a flask of vodka among the ship's remains sparks a series of inexplicable and terrifying events. After consuming the vodka, crew members begin exhibiting strange symptoms, hinting at a much darker secret harbored by the sunken Soviet vessel. The illness rapidly spreads, and the team soon realizes they are dealing with a genetic mutation that threatens their lives. Isolated at the bottom of the ocean, with a dwindling supply of air and an unknown menace lurking within their own ranks, the group's struggle for survival becomes desperate. As they attempt to contain the situation, they face the horrifying realization that the mutation does not just kill; it transforms its victims, challenging their very humanity.