A sudden chain of bizarre occurrences stirs the military into action when an Arctic radar station is destroyed and an aircraft is attacked. Colonel Joe Parkman is assigned to investigate the mysterious events, discovering a strange, gargantuan insect claw at the site of the crash. Realizing that they are dealing with an unprecedented threat, he recruits Dr. Ned Jackson, a paleontologist, and Marge Blaine, a photographer, to aid in identifying the creature. Dr. Jackson determines that the claw belongs to a giant praying mantis, released from its prehistoric ice prison by volcanic activity.

As reports of destruction spread across North America, it becomes clear that the deadly mantis is migrating south, leaving chaos in its wake. The military struggles to contain the beast, deploying various strategies to combat the giant insect. Survivors recount their terrifying encounters while scientists race against time to predict the creature's movements and devise a plan to stop it. The mantis continues its relentless journey, posing an ever-growing danger to populated areas if left unchecked. The tension escalates as humans grapple with their vulnerability against this ancient predator.