The hit series continues! The American submarine Nebraska sends in a team to rescue crewmen trapped in a mysterious underwater temple. The team encounters deadly's traps inside the temple and Commander Hamish realizes these traps aren't meant to keep them out, but to keep something else in, something that is hunting his crew! Meanwhile, things aboard the sub are no better: some men become literally haunted by the ghosts of their past, while others fall prey to hallucinations. Isolated incidents grow more numerous, and it is up to Hamish to keep order on board the sub so that he can rescue his crew from within the sanctum.