The crew of seaQuest rescue a warden and his only prisoner from beneath the ice cap. The prisoner escapes and reveals that he holds a deadly toxin which will be released unless the crew does as he says, which is launching the seaQuest's missiles against the UEO.
- On the way to the Antarctic polar ice cap, Bridger rescues a warden and his prisoner. However, the prisoner escapes and holds the seaQuest hostage with a dangerous toxin.
The prisoners in the ice cap are literally under ice, i.e. kryogenically frozen. Expecting to pick up a group of prisoners and the warden, Capt Bridger (Roy Scheider) rescues only one kryogenic capsule and the man claiming to be the warden. The prisoner was a brilliant scientist, Dr. Zellar (Alan Scarfe) whose infamous works were known the world over.
The 'warden' engages several of the crew in games of the mind, e.g. chess but the real games turn more deadly when the 'prisoner' thaws and it is discovered that he was actually the warden and Dr. Zellar was free and masquerading as the warden.
There is a hole in the thawing warden's chest that provided a space for Dr. Zellar to smuggle a deadly toxin on board. The subsequent cat-and-mouse games pit Zellar against Bridger and crew trying to prevent the release of the deadly toxin that could kill everyone aboard the SeaQuest and more.
Even Dr. Westphalen discovers a personal vendetta against Zellar, more than his playing deception games with her. Her late brother, also a Dr. Westphalen, was a victim of Dr. Zellar's deadly whims. Does she get even, preserve her conscience or devise a way to do both?