Baron Frankenstein is blackmailed by Dr. Praetorious into reviving his monster and building a mate for it.

The mythical story of a dangerous half-human, half-fish creature lurking in the depths of the Amazon. After discovering a unique prehistoric claw fossil on an expedition deep in the jungle, archaeologists investigates its origins which lead them directly to a mysterious creature. Led by marine life specialist David Reed, the men try to capture the monster who has become obsessed with David's assistant Kay.