Commander Hart is in charge of the submarine Nautilus Rex. Dr. Tate brings aboard a rare vintage wine called Summerween, which results in the death of Chief Brody from cyanide poisoning. The crew is locked down, as Hart investigates, discovering that Brody's mug was specifically poisoned and the Summerween merely a distraction. As Hart investigates, the submarine suffers a catastrophic malfunction to its port thruster, which leads to further murders and the sub sinking deeper.