In 1943, the Navy submarine US Lionfish was inexplicably shut down: its commander, Tony Sterling, gone without a trace. Seventy years later, Sterling's grandson, professor Peter Williams, is recruited by a top-secret government agency to investigate. Aboard the Lionfish, Peter and his team uncover clues to the sub's cryptic past, and are plunged into a terrifying supernatural journey that will take them across the dark abyss of time, with history hanging in the balance.