I can see why the exotic Ms Steele has become a cult figure. With her odalisque eyes, sensuous mouth, and statuesque figure, she's a real scene grabber. Here she's got dual roles. First she's a philandering wife, Muriel, murdered by her vengeful Dr. Frankenstein husband, Stephen. Then she's Muriel's blonde sister Jenny who's being driven to madness by Stephen for her newly inherited fortune. Seems Stephen (Muller) has got this infernal potion that brings on ghostly dreams that he inflicts on hapless Jenny. Jenny's long been mentally frail, but now threatens to go over the edge. Interestingly, however, it's not always clear whether the ghostly figures are real or potion induced. Good thing Doctor Dereck (mase) arrives at the nightmarish castle to help.
The movie's richly photographed with glaring close-ups and deep shadow that highlight the Gothic horror. Unfortunately, the script's pretty sloppy, as other reviewers point out. Still, that may be the result of a poorly edited version that I saw. Nonetheless, to the movie's detriment, the suspense doesn't so much intensify or build to a climax as it simply bumps along from one narrative episode to the next.
With his patrician features, actor Muller makes a visually apt villain, even though he doesn't project enough needed evil. At the same time, actress Line as the dishy housekeeper Solange can come clean my house any day. Seems however she's really an elderly woman that maestro Stephen has made temporarily young, so maybe not.
Overall, the movie's a rather classy horror film, not as cheezy as most. Also, mark me down as a new member of the Barbara Steele fan club.