Watch Night of the Doomed aka Nightmare Castle

The dark goddess of Italian horror, Barbara Steele, delivers a dual performance as a cheating wife who is chained, whipped and tortured to death along with her lover by her sadistic scientist husband Arrowsmith, and as her unstable blonde stepsister whose fate may be even worse. Steele and her lover return from the grave to seek revenge as the surviving sister is slowly driven mad by Arrowsmith.