In the remote Florida Everglades, a pair of giant, intelligent leeches inhabit an underwater cave. These monstrous creatures capture unsuspecting locals, dragging them to their lair where they keep their victims prisoner and slowly drain their blood. One of the earliest victims is the notorious local, Liz Walker (Yvette Vickers), after a series of scandalous events involving her husband, Dave Walker (Bruno VeSota), and her secret lover. Liz soon finds herself trapped with her lover in the clutches of the leeches. Game warden Steve Benton (Ken Clark), together with his girlfriend Nan Grayson (Jan Shepard) and her father, Doc Grayson, undertakes an investigation into the mysterious disappearances. Their search leads them to the underwater cavern. The story reaches its climax when Steve, Doc, and a group of state troopers manage to destroy the monsters by blowing up the cave with dynamite. Cast Highlights: - Ken Clark as Steve Benton - Yvette Vickers as Liz Walker - Jan Shepard as Nan Grayson - Michael Emmet as Cal Moulton - Tyler McVey as Doc Grayson - Bruno VeSota as Dave Walker - Gene Roth as Sheriff Kovis - Dan White as Porky Reed - George Cisar as Lem Sawyer - Guy Buccola as Giant Leech - Joseph Hamilton as Old Sam Peters - Walter Kelley as Mike - Ross Sturlin as Giant Leech Runtime: 62 Minutes