AllMovie

When a scientist team at Ice Station T is mysteriously killed, the Seaview must investigate the cause. Complicating the mission are three not-wholly-welcome guests -- Dr. Reisman (David Opatoshu), a brilliant but personally unpleasant researcher who once worked for Hitler's government; Julie Lyle (Jill Ireland), a young agricultural researcher; and Philip Wesley (John Milford), a representative of the corporation financing the mission with the government. Each has his own agenda, and one may be an enemy spy -- but unknown to all of them, the plankton research project they're working on has created a monstrous, incredibly dangerous creature.