The Venture, an old Trident nuclear sub retrofitted for research has picked up an ancient and powerful artifact on the ocean floor and brought it on board.  Called the Hades Stone, it allows the dead to return and join the living. Evil things appear in this world – phantoms. demons and an ancient being called the Stone Keeper, the guardian of the Hades Stone. The demons attack, killing the crew. The portal inside the Hades Stone fills the submarine with the accursed souls of the past.  Jack Bavaro, head of Interceptor Force, has gathered his best operatives  they know the submarine has been commandeered and they know they cannot just torpedo it – a navy attack submarine that tried was instantly destroyed by the demon-ridden submarine. They must enter the Venture and do battle  at the bottom of the ocean.