In a remote South American rubber plantation, overseer Barney Chavez kills his employer, Klaas Van Gelder. Witnessed by a local native witch/maid, Barney is placed under a voodoo curse. He marries his boss's widow, Dina Van Gelder, but begins transforming nightly into a demon gorilla. Police Commissioner Taro and local physician Dr. Viet investigate a series of animal killings and close in on Barney.

Raymond Burr
as Barney Chavez

Barbara Payton
as Dina Van Gleder

Lon Chaney Jr.
as Commissioner Taro

Tom Conway
as Dr. Viet

Paul Cavanagh
as Klaas Van Gelder

Gisela Werbisek
as Al-Long

Carol Varga
as Larina

Paul Maxey
as Van Heusen

Woody Strode
as Nedo

Martín Garralaga
as Native