Something is killing undersea miners in the Mariana Sea Basin, and officer Will Murdack (Dean Cain) of the Deep Submersible Division is enlisted to investigate. At 35,000 feet below, he has to deal with 24-hour darkness, decompression sickness and a ticking clock of claustrophobia that has intensified the miners' rage. It's a race against time as the mystery becomes increasingly deadly. Can Murdack save the miners -- and, ultimately, himself?