Frederick Loren (Vincent Price), an eccentric millionaire invites five people to a party he is throwing for his fourth wife Annabelle (Carol Ohmart) in an allegedly haunted house he has rented, promising to give each $10,000 with the stipulation that they stay the entire night in the house after the doors are locked at midnight. The guests are test pilot Lance Schroeder (Richard Long (actor)), newspaper columnist Ruth Bridges (Julie Mitchum), psychiatrist Dr. David Trent (Alan Marshal (actor)) who specializes in hysteria, Nora Manning (Carolyn Craig) who works for one of Loren's companies, and the house's owner Watson Pritchard (Elisha Cook). All are strangers to both the Lorens and each other, with their only commonality a desperate need for money.