CIA agent Wheeler (Jean-Claude Van Damme) and his beautiful partner Mel are hunted by a mysterious organization while protecting a confidential document. Mel dies and Wheeler is arrested. When Wheeler wakes up, he finds himself imprisoned in a nuclear submarine, a black prison set up by the CIA in the deep sea. He has become a traitor who betrays state secrets. In addition to Agent Patrick who tortured Wheeler, there are Wheeler's mentor Edward, female trainee Cathy and the imprisoned German agent Marco (Dolph Lundgren) on the submarine. Who is an ally and who is an enemy among them? Some are interested in the confidential documents in Wheeler's hands, while others are more interested in leaving the deep sea and regaining their freedom. Wheeler must find his teammates, work together to escape, and prove his innocence...