Villain(s)  Gigantic intelligent leeches

Actor(s):  Ken Clark, Yvette Vickers, Jan Shepard, Bruno VeSota

Brief Description  Attack of the Giant Leeches (1959) is a low-budget black-and-white horror-sci-fi film directed by Bernard L. Kowalski and produced by Gene Corman (with Roger Corman as executive producer). Set near the Florida Everglades, the 62-minute film follows local swamp inhabitants terrorized by intelligent, human-sized mutant leeches living in an underground cave system.

Plot:
The film takes place in a remote, desolate swamp region in the Florida Everglades. Local poachers and hillbillies begin encountering bizarre, man-sized creatures with large suckers on their bodies, but the community dismisses these sightings as drunken hallucinations. The horror begins in earnest due to a volatile love triangle. Dave Walker, the local store owner, discovers that his beautiful but unfaithful wife, Liz, is having an affair with a local man named Cal. Enraged, Dave tracks them down in the swamp with a shotgun and forces them into the water at gunpoint. While submerged, Liz and Cal are attacked and dragged underwater by giant, mutant leeches. Terrified and wracked with guilt, Dave is blamed for their disappearances and is thrown in jail, where he ultimately hangs himself out of despair. Game warden Steve Benton and Doc Greyson refuse to accept the official stance that the missing people were simply victims of standard alligator attacks.

They deduce that a new apex predator is lurking in the water. It is theorized that atomic radiation from nearby Cape Canaveral caused ordinary leeches to undergo extreme gigantism. Steve organizes a search party, but the local sheriff remains skeptical until more bodies wash ashore. The investigators discover that the giant leeches do not immediately kill their prey; instead, they drag their victims to an underwater cavern network, keeping them alive while slowly draining them of blood over several days. Steve uses SCUBA gear and a spear-gun to dive into the murky depths to confront the monsters. After discovering the horrific underwater lair and realizing how many creatures occupy the swamp, the authorities decide to destroy the caverns using dynamite. The underwater explosions successfully kill the monsters, causing their bloated, plastic-looking bodies to float to the surface. However, the final moments of the film imply that some creatures may have survived as an eerie gurgling sound echoes from the reeds.