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.