In a oil company's laboratory, the air conditioning fails, and a primate creature attacks a scientist. The creature, and others like it, begin going on a rampage throughout Chicago. The oil company was experimenting with cell samples brought back from the Antarctic, which began growing when exposed to heat. Now these bizarre missing links are wrecking havoc. Despite the government cover-up, Kolchak investigates, and must track the creatures down to their lair beneath the old nuclear-research labs of the 50's.