Navy Commander Hal Roberts leads an expedition to investigate reports of a mysterious warm water inland lake in Antartica. His small party, including beautiful reporter Maggie Hathaway, is forced into a volcanic crater where they find themselves trapped in a lush tropical environment that has survived from the Mesozoic Era. Fighting carnivorous plants and dinosaurs, they are both helped and hindered by Dr. Carl Hunter, a megalomaniac survivor of an earlier expedition, as they struggle to survive and escape this hostile environment.
