I watched Mario Caiano's Nightmare Castle yesterday. I had seen it before, but found I got more out of it this time around, thanks to having become more aware of Italian Gothic in the interim.
The story itself is one of those standard combinations of the supernatural and quotidian, as Paul Muller's scientist murders his first wife Muriel and her lover, then marries Muriel's half sister Jenny - both being played by Barbara Steele - and conspires with his mistress to use Jenny for a vampire-style blood transfusion to save his mistress's life.
Thus Steele gets to do her usual good / bad, pain / pleasure, sadistic / masochistic dualisms, here further emphasised by having Jenny being blonde in contrast to the dark Muriel, who also returns from beyond with one side of her face horribly scarred.
This last aspect I found quite Satanik-like, though unlike Satanik's alter-ego, Marny Bannister, whose scraped-back hair makes her disfigurement obvious, here Steele's character hides her scars behind i lungi capelli della morte until the time is right for the shock revelation.
There's also a spot of mask action, as Muller attempts to drive Steele #2 mad by drugging her and setting up weird nightmares. Somewhat Opera:
Also of interest are the little intertextual nods. At one point early on Muller's character announces that he's going to a conference in Edinburgh, recalling the Scottish setting of Riccardo Freda's The Ghost. That film and the director's earlier Horrible Secret of Dr Hichcock also seem to be referenced via the original surname of Muriel and Jenny, Hampton - just like Freda's pseudonym of choice.