In a tributary of the Amazon, a monster – half-man, half-fish – is captured and placed in a reservoir in a Florida national park to be observed by scientists.

The ice-cold diva Paula ruthlessly exploits the guys she dates. While blackmailing the married Don with a recent one-night-stand, she has a secret affair with Henry, who works as researcher for the weekly authentic TV show "Crime of the Week", which Don writes for. When Henry fails to help her to a role, she insults him deadly... and ends up dead herself. Now Don desperately tries to hide his traces, but Henry sabotages his efforts and suggests he write the unsolved murder case for next week's show...