Three self-described Teen Angels, Brenda, Dee Dee and Taffy found a caveman encased within a prehistoric block of glacial ice, and they set him free. Turns out, their newfound companion came in handy when they needed muscle while solving mysteries.

Gaira, a humanoid sea beast spawned from the discarded cells of Frankenstein’s monster, attacks the shores of Tokyo. While the Japanese military prepares to take action, Gaira’s Gargantua brother, Sanda, descends from the mountains to defend his kin. A battle between good and evil ensues, leaving brothers divided and a city in ruins.

A spy steals a secret military device, then hijacks an airliner to get away. The airliner crashes in the wilderness & the survivors are threatened by a raging forest fire.