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Although they were inside the exploding kelp plant, Terry (Ralph Byrd), Jean (Maxine Doyle), and Snapper (Lee Ford) all emerge no worse for wear. Boroff (Bela Lugosi) and his gang arrive to their secret island hideaway but discover that one of the cases of disintegrating gas has been left behind. Realizing that Jean's brother, Dick (Allen Connor), may be able to produce an antidote, Boroff sends a couple of his men to kill him. The scientist is abducted from his laboratory but the getaway truck accidentally leaks a trail of acid. When Terry finally catches up with the abductors, the truck is on fire with Dick trapped inside. As our intrepid hero struggles to free his friend, the brakes give way and the truck plunges over a cliff and into the ocean below.