What Was the Terrifying Secret of the Cellar?
Terry and Ann are two "swingers" who spend the night in a spooky old house, where they're subjected to bizarre sexual experiments by Mr Bradley and his deranged sister.
- Release Date: December 11, 1968
- Runtime: 80 minutes
- Production countries: United States of America
- Original Title: Behind Locked Doors
- Original Language: English
Genres: Horror
Actors: Joyce Danner, Daniel Garth, Eve Reeves, Ivan Agar, Irene Lawrence