A mad scientist transforms himself into an aquatic killer.
A mad scientist (and apparent former Nazi) unleashes his master plan: to transform himself into a mutated walking catfish, gain revenge on those who have spurned him, and kidnap nubile young women to similarly transform so that he can breed. Or something like that.—<[email protected]>
A shuffling, evil marine biologist/janitor who speaks only in voice-overs develops a process to turn people into super-powerful amphibious sea creatures. Once he transforms himself, however, he seems to lose focus, as he starts Windexing a nearby pond. Only later does he vaguely start chasing after nubile women so that he can transform them as well, mate, and produce a race of super beings which will RULE THE WORLD!!—Leo L. Schwab <[email protected]>
In his laboratory, mad scientist Dr. Kurt Leopold contemplates his former colleagues' derision for his "formula", "ZaAt", a compound that can transform humans into sea creature hybrids. He injects himself with the serum and immerses himself in a tank, emerging as a catfish-like monster. In his new form, Leopold releases walking catfish across the town's lakes and rivers, and releases "Zaat" into the water supply, rendering many of the townspeople ill. All the while, Sheriff Lou Krantz and marine biologist Rex Baker investigate the strange happenings with the local catfish and the waterways.
Leopold turns his attention to killing those who mocked his work. He murders former colleague Maxson and his family on a boat, followed by associate Ewing in his home. Leopold returns to the lake where he kidnaps a young female camper. Taking her back to his lab, the doctor straps her in a mesh basket beside the large water tank, with the intention to make her his mate. However, due to her struggling, the equipment malfunctions, and her corpse, partially transformed, is pulled from the tank.
Baffled by the deaths, Rex contacts an organization known as INPIT, which sends scientists Martha Walsh and Walker Stevens to the town. Following kidnapping Martha, Leopold heads towards his lab, followed by Walker, who has picked up Leopold's radioactive trail. The doctor arrives at the lab with Martha, where Rex and Lou happen to be searching. A fight ensues and Leopold fatally wounds them. He injects Martha with "Zaat", readies her to be dunked into the tank, and makes his getaway with canisters of the compound. Martha's transformation fails, and she is saved from the tank by a dying Rex, although she appears to be in a trance and immediately follows Leopold into the sea.
