Rescuers board an experimental craft hoping to reach the crew of a disabled American submarine trapped in an underwater canyon before their air supply runs out - but both vessels face a whole host of challenges and hazards in the depths of the ocean. Action adventure, starring Charlton Heston, David Carradine and Stacy Keach.

The USS Neptune, a nuclear submarine, is sunk off the coast of Connecticut after a collision with a Norwegian cargo ship. The navy must attempt a potentially dangerous rescue in the hope of saving the lives of the crew.