A research station in Antarctica is trying to reach the Seaview without success, as a current snow storm is causing radio interference. As the wife of the researcher Robert Pennell goes to bed, she turns on two heaters, which causes samples of plankton to grow at an alarming rate, which ends up overtaking the Pennells after several minutes. Sabotage of the Seaview, finding the research station destroyed, and having the monstrous plankton reign destruction upon the sub follows, all of which must be rectified in order to save the Seaview and all on board.