After intrepid working girl Mary Carter becomes the new owner of a reputedly haunted mansion located on Black Island near the Cuban coast, a stranger phones to warn her to stay away from the castle. Undaunted, Mary sets sail for Cuba with a stowaway in her trunk -- wise-cracking Larry Lawrence, a radio announcer who helps Mary get to the bottom of the voodoo magic, zombies and ghosts that supposedly curse the spooky estate.
Mary Carter inherits her family's ancestral home, located on a small island off Cuba, and, despite warnings and death threats, decides to take possesion of the reputedly haunted castle. She is joined by radio broadcaster Larry Lawrence who, believing he has killed a mob gunsel, flees New York with his butler, Alex. Once on the island the threesome enter the eerie castle and after viewing the ghost of one of Mary's ancestors and fighting off a menacing zombie, they find the key to the castle's treasure but are interrupted by an all-too-human foe.