Frozen for centuries, the Brute is released when a nearby power plant causes the temperature to rise 5 to 6 degrees, melting his frozen prison.
Three young boys have the misfortune of wandering into his cave. Two are horribly killed by the Brute, while one manages to escape to notify the authorities.
The police arrive to gas the cave and force the Brute out into the open. A tranquilizer dart subdues the creature, but not before he smashes a TV cameraman against the wall of the cliff.
The Brute awakens behind bars, his fate to be decided by a judge. The father of the dead boys, Mr. Carlson, wants vengeance, while Dr. Turner, an anthropologist, wants to study the Brute in captivity. The judge rules in favor of Dr. Turner, much to the dismay of Mr. Carlson.
Months pass as Dr. Turner and the Brute begin to form a bond. While leaving the lab one evening, she is struck from behind by Mr. Carlson. He releases the Brute, in hopes that he will be blamed for attacking Dr. Turner. Seeing the injured Doctor, the Brute turns on Mr. Carlson, crushing him against a concrete wall.