In a laboratory somewhere along the coast of Florida a scientist is working feverishly on a grisly experiment. Known by the local transients only as the “Beach Bum” he is trying to create his vision of ultimate beauty, a mermaid. But test after test end up in failure, leaving behind a series of mutated abominations. Still, the experiment continues.

At a nearby beach the mutilated body of a man turns up, his female companion, missing. Detective Elizabeth Wayne heads up an investigation to find the killer, her only leads being the body of the murdered man, a single witness so drunkenly asleep that he claims to have neither heard nor observed anything, and a group of strange looking scales found at the scene.

Enlisting the aid of marine biologists Craig and Mike, Detective Wayne attempts to unravel the mystery behind the strange scales which defy identification. She feels that somehow they are key to what is going on.

As the mystery deepens and more girls end up missing, Detective Wayne tries one last ploy to draw out the killer; use herself as bait!