A depraved bloodsucking sinister force is terrorizing the backwoods. When flirtatious sexpot Liz Walker (Yvette Vickers) is thrown into the swamp by her jealous husband (Bruno VeSota), she's taken hostage by giant leeches and held captive in their underwater cavern of horror. Other townsfolk are soon abducted by the leeches, joining Liz in the monsters' subterranean lair.

Bruno played the owner of a grocery store who hangs himself.