James Murphey is a rugged cryptozoologist, who thirty years earlier, during a trip to Loch Ness, Scotland, had a fatal encounter with the fabled "Nessie" creature that killed his father, and left James with deep facial scar. Twenty years later, James is hunting for Nessie, when his search leads him to the sleepy town of Pike Island, Ashburn, on Lake Superior. Hiring Josh Riley as his guide, James and Josh bond over their mutual scientific interests and deceased fathers, while James tries to convince Josh's mother, Sheriff Karen Riley, that the 60-foot plesiosaur is killing and breeding.

Navy Commander Alan Roberts is assigned to lead an expedition to Little America in Antarctica to investigate reports of a mysterious warm water inland lake discovered a decade earlier. His helicopter and its small party, including reporter Maggie Hathaway, is forced down into a volcanic crater by a fierce storm. They find themselves trapped in a lush tropical environment that has survived from prehistoric times.

The heat of a meteor crashing into the lake incubates a prehistoric egg, which grows into a plesiosaur-like monster that terrifies the community.