The venture, an old trident nuclear submarine retrofitted for research has picked up an ancient and powerful artifact off the ocean floor and brought it onboard. Called the Hades Stone, it allows the dead to come back through and join the living. No one has entered the portal, but evil things have come back through into our world - phantoms, demons and an ancient bad-ass known as 'the stone keeper, guardian of the Hades Stone'. The stone keeper and his stone demons attack, killing the entire venture crew. The portal inside the Hades Stone fills the sub with the accursed souls of the past. Jack Bavaro, head of the interceptor force, has gathered his best operative minds. Weapons developer Joe Murray, former New Orleans detective Leanne Potts, parapsychologist Dr. Rebecca Solomon, nave expert diver Kyle Hudson and engineer Paul Cutler. Bavaro and the Phantom Force realize the Hades Stone and its demons may have taken over the sub and simply destroying the submarine with a torpedo won't work; a navy attack submarine tried and was instantly wiped out by the ghostly sub. So now it's a mission for the Phantom Force team to stop the venture before it attacks again and retrieve the Hades Stone. Armed with paranormal gear like particle guns and vapor grenades, the team drops through the water in jet-divers. They enter the venture. As the team explores the sub, the Hades Stone opens up and unleashes the Stone Keeper and his demons. Then it's a battle at the bottom of the ocean for the Phantom Force