Pit and the Pendulum (1961)

(Costal Spain; 1546 and flashbacks)
IMDb

When his sister dies suddenly, an Englishman named Francis (John Kerr), travels to coastal Spain to investigate her death. There he meets his late sisters husband Don Nicholas Medina (Vincent Price) and his visiting sister Catherine (Luana Anders). Though at first the two try to mislead him about how Elizabeth (Barbara Steele) died, a family friend and doctor (Antony Carbone) forces them to face the truth. You see Nicholas’s father was Sebastian Medina, a famed sadistic torturer of the Spanish Inquisition (nobody ever expects that), whose instruments of pain had came to cryptically fascinate Elizabeth, until she accidentally killed herself with one of them. Or did she?

In short order strange occurrences start to happen around the castle, is it Elizabeth’s ghost, or did she never die, or is the poor Don Medina acting out his grief via a slow psychological breakdown. Also there’s the matter of what happened to the Don’s late mother. Pretty riveting stuff, the creep manages to work its way through the light camp, creating an enjoyable and slightly disturbing picture.