A scientific expedition searching for fossils along the Amazon River discover a prehistoric Gill-Man in
the legendary Black Lagoon. Drugged and captured, the creature becomes enamored with the head scientist's
female assistant. The lonely creature, "a living amphibious missing link," escapes and kidnaps the object
of his affection. The chief scientist then launches a crusade to rescue his assistant and cast the ominous
creature back to the depths from where he came.