In a dystopian future, the Tri-Oceanic Corp has assembled a group of undersea miners for a challenging 90-day operation at the depths of the Atlantic Ocean. The company's head, Miss Martin, recruits Steven Beck, a skilled geologist, to oversee both mining and command the underwater facility. The crew comprises eight members, including Dr. Glen 'Doc' Thompson, the local physician; Elizabeth 'Willie' Williams, a resolute female miner; the bold Buzz 'Sixpack' Parrish; the kind-hearted Justin Jones; Tony 'DeJesus' Rodero, an adept mechanic; Bridget Bowman, a technician skilled with computers; and G.P. Cobb, a seasoned miner responsible for various maintenance tasks.
The mission takes an unexpected turn when, during a drilling exercise, Sixpack encounters a wrecked Russian cargo ship, the Leviathan. Unable to communicate over the radio, Willie ventures out, discovering Sixpack enchanted by what he perceives as treasure. A video feed reveals disturbing details: the ship is still officially listed as operational in the Baltic Sea.
Upon exploring the wreck, the crew unearths some eerie items, including crew records and a troubling video from the Leviathan's captain. This footage hints at a horrible fate, detailing how crew members suffer from mysterious ailments—implying they’re afflicted by an unknown infection or plague. Among the findings, Sixpack discovers a flask of vodka, which he clandestinely stashes away, igniting a chain of events when Bowman persuades him to share.
That night, the two watch the captain's tape together, revealing a visibly sick crew on board the Leviathan, which leaves Beck and Thompson deeply concerned about the implications for their own crew.> "Something's off," warns the captain before the recording abruptly cuts off. The next day, Sixpack falls ill with disfiguring lesions, and despite Dr. Thompson’s efforts to identify the cause, he can only speculate on a possible genetic alteration. Tragically, Sixpack succumbs to the illness, prompting Beck and Thompson to conceal the truth to prevent panic.
As they grapple with this grim reality, Bowman also begins to exhibit symptoms, which culminate in a terrifying discovery: she finds Sixpack's corpse undergoing horrific mutations. With fear mounting, Beck and Thompson urge Ms. Martin to initiate an emergency evacuation, but she frustratingly cites bad weather as a hindrance.
In an even darker turn of events, Bowman succumbs to despair, taking her own life in the shower. The bodies of Sixpack and Bowman are disposed of in secret, but as the crew attempts to hide the truth, they encounter chaos when a mutated creature emerges from the discarded remains, attacking Cobb just as they attempt to expel it.
Amidst the rising tension, the crew realizes that the Leviathan was a site for genetic experimentation, with its vodka potentially tainted with mutagenic cells that transform crew members into horrifying entities. As they fight for survival, their numbers dwindle at the hands of this relentless monstrosity, leading to a desperate attempt to escape.
As their underwater base deteriorates, Beck, Jones, and Willie decide to use specialized dive suits to make a break for the surface. Despite a fierce encounter with the creature, they manage to reach the water's surface, only to be confronted by the coast guard.
In a heart-wrenching moment, Jones sacrifices himself to fend off the creature, buying Beck enough time to eliminate the horror with an explosive. Once aboard the rescue ship, the two survivors come face to face with Miss Martin again. Her insincere smile as she congratulates them prompts Beck to deliver a swift punch, putting her in her place and emphasizing the horror they endured together.
