Geologist Dr. Carl Maia discovers the fossil of a clawed hand in the Brazilian jungle. An investigation at the Morajo Bay Institute does not provide any clarity, so Maia sets out on an expedition to investigate the black lagoon more closely. After the first participants are found dead, the cause is soon revealed in the form of a human-like, scale-covered beast, which immediately falls in love with Maia's colleague and fiancée Kay Lawrence...

Loan of the film print with kind support of Universal.