A young girl is found wandering in shock in the New Mexico desert near White Sands by two state troopers. When they investigate they find that the trailer that she was staying in with her parents and sibling had been destroyed. They also find that kindly old Gramps Johnson who ran the local store was also killed in a mysterious way. A lone print found in front of the little girl's trailer is sent to the FBI in Washington for identification.
Dr. Medford and his daughter Dr. Pat Medford come to New Mexico after identifying the print as belonging to a species of ant that had mutated after the first atomic bombing 9 years before in 1945. They find and destroy the New Mexico nest but not in time to prevent two young queen ants from escaping.
One of the ants starts a nest on a military ship at sea. Another ant makes her way to the drain system of Los Angeles. The hunt is on to see if the nest can be destroyed before the ants destroy the world as we know it.