Classic creature feature. A scientist and a government agent join forces to investigate a series of mysterious deaths at sea, only to discover a horrifying secret under the waves. (1955)

A marine biologist and a government agent investigate mysterious deaths and rumors of a sea monster in a secluded ocean cove, and find themselves involved with a marine biology professor conducting secretive experiments, international spies trying to steal his secrets, a radioactive light on the sea bottom, and the malevolent thing which guards it.