The Unknown Terror

The mysterious disappearance of Jim Wheatley (Charles H. Gray) while exploring the legendary "Cave of the Dead" brings his sister Gina Matthews (Mala Powers) and her husband Dan (John Howard) to what Dan calls the "shores of the Caribbean." But at a pre-expedition party, Gina is taken aback when Pete Morgan (Paul Richards) arrives uninvited. Pete, Gina and Dan had been a romantic triangle. Pete saved Dan's life on an earlier expedition, but was injured and now limps on his permanently damaged right leg; after the injury, Gina and Dan married. He convinces Dan to take him on the new expedition.