Cast: James Arness, Joan Weldon, James Whitmore, Edmund Gwenn, Onslow Stevens, Sean McClory, Chris Drake, Sandy Descher, Mary Ann Hokanson, Don Shelton, Fess Parker, Olin Howlin, Harry Tyler, Grandon Rhodes, Leonard Nimoy, Matthew McCue, Lawrence Dobkin, Ann Doran, Robert Scott Correll, Richard Bellis, John Beradino, Robert Berger
A light airplane and a Police car make a coordinated search of the New Mexico desert. Police Sgt. Ben Peterson (Whitmore) and Trooper Ed Blackburn (Drake) find a six-year-old girl (Descher) walking among the Joshua trees, clutching a doll. She is speechless, wide-eyed, in shock. Nearby, they find a station wagon and a ransacked house trailer, part of its wall torn off. They find a piece of cloth torn off from the girl’s dress, and Sgt. Peterson figures she belongs with the absent owners of the trailer. A search of the surroundings finds no one, and no footprints or tire marks, only a strange impression in the sand, like the track of an animal. The Police make a cast of the unusual animal track. As an ambulance drives away with the girl, the wind carries a peculiar sound, a high-pitched trill. At a general store a few miles away, Peterson and Blackburn find everything turned upside down and part of a wall torn off. The money in the cash register is untouched, but the torn body of the storekeeper lies in the basement, the barrel of his rifle bent at an angle. As darkness falls, the Policemen call in their grisly find and Sgt. Peterson drives off, leaving Trooper Blackburn to guard the store. Alone, Blackburn hears the shrill sound he had heard at the trailer site and walks outside to investigate, the wind howling about him. In the dark, gunshots are heard, and then Blackburn’s scream. The Police investigate the string of mysterious attacks and killings, including Blackburn’s. They identify the missing family of the girl as that of a vacationing FBI agent. Special Agent Robert Graham (Arness) joins the investigation. Working with Sgt. Peterson, Graham asks that the cast of the strange animal track be sent to Washington for analysis. The Police and Graham are joined in their investigation by Dr. Harold Medford (Gwenn) and Dr. Patricia Medford (Weldon), a father/daughter team from the Department of Agriculture. Dr. Harold Medford, an entomologist, has a theory about the animal tracks. Sgt. Peterson, Graham and the Medfords pay a visit to the little girl at the hospital where she’s recovering. Aided by Patricia, her father performs an experiment. Still speechless and unresponsive, the little girl is given a whiff of formic acid and immediately becomes very agitated. She screams hysterically, “Them! Them!” The elder Dr. Medford believes that the animal tracks are from ants, mutated to enormous size as a result of radiation from atomic bomb testing in the desert near Alamogordo. Back at the place where the ransacked house trailer was found, Patricia searches for more of the strange tracks, and hears the shrill sound. A moment later a huge ant, its head two feet wide, appears from behind a sand dune. Patricia’s screams attract Graham and Sgt. Peterson, and they manage to kill the looming ant. But the monster is only one of many. The nest of the giant ants is located and attacked with phosphorous and cyanide gas. Protected by special suits and masks, Graham, Sgt. Peterson, and Patricia Medford enter the immense nest. Deep underground, they evade the crushing mandibles of the remaining ants and kill them all, but find that two young queens have hatched and flown away to establish new nests. They must find them and kill them, for the ants have an instinct and talent for industry, social organization, and savagery that makes man look feeble by comparison. Music by Bronislau Kaper. Special effects by Ralph Ayres. Story by George Worthing Yates.