A young archaeologist believes he is cursed by a mask that causes him to have weird nightmares and possibly to murder. Before committing suicide, he mails the mask to his psychiatrist, Dr. Barnes, who is soon plunged into the nightmare world of the mask.

Psychiatrist Allan Barnes is visited by archeologist Michael Radin, who claims he is under the evil spell of a ritual mask he unearthed in the ruins of an ancient city. The mask forces him to commit murder. Barnes expresses skepticism, and the highly emotional Radin rushes from the office, returns to his room, and, after mailing the mask to Barnes, commits suicide. Upon receiving the package, the curious doctor dons the mask and experiences eerie and frightening hallucinations. Though shaken by the experience, he informs his fiancée, Pamela Albright, that he plans to continue experimenting with the unearthly object. Thinking of his safety, Pamela takes the mask to a museum, but Barnes breaks in at night and steals it. After two more experiences with the mask, he suddenly becomes obsessed with the desire to murder his pretty receptionist, Jill Goodrich. But as he tries to strangle her, she gashes his face and escapes into the night. Returning to Pamela, Barnes forces her to put on the mask, and he becomes enraged and tries to choke her when she experiences no reaction. The police arrive in time to rescue her. Restored to its place in the museum, the mask seems to attract another young man, a museum visitor.