Dynamite fishing in a rural swamp revives a prehistoric gill monster that must have the blood of human females in order to survive.

When a local begins fishing with dynamite in Bog Lake, something a bit larger pops to the surface: a green, bug-eyed mutant monster awakened from a long sleep, which promptly begins killing and eating fishermen who stumble across its lair. When biologist Ginny Glenn discovers the creature's evolutionary nature, the local sheriff decides to use most methods to destroy the tenacious beast.—Ørnås