Well, this is a peculiar one. A muddle of insanity, terror, murder and incest, it's a faintly sickening thriller. Directed by Peter Sykes in an erratic, free-form fashion, it's quite difficult to make sense of for much of its ninety minute runtime. At times I wondered if the revelation would be that all the characters were mad, which might well be true. It's all fairly hysterical, with every member of the cast overacting for maximum effect. Robert Hardy plays Count Zorn, a twisted landowner who keeps his two full-grown children imprisoned in his mansion home. His sister-in-law Hilda (Yvonne Mitchell) keeps the two youngsters under lock and key. Emil (Shane Briant) is a sickly, pale thing, yet still has the strength to repeatedly escape into the village and murder young women, while his sister, Elizabeth (Gillian Hills), with whom he has an incestuous relationship, manages a proper escape before being reapprehended and subjected to questionable medical treatment.
The question of just who is insane and why the murders are being committed runs through the film. Patrick Magee gives his usual bizarrely mannered performance as Dr. Falkenberg, a theoretical psychologist who has developed a controversial treatment based on magnetic fields that supposedly permeate the universe. This Mesmer-inspired method seemingly allows him to probe into Zorn's disturbed psyche and reveal the truth of his madness. It's something of a flipside Fear in the Night, a psychological thriller posing as something supernatural. Demons of the Mind at first appears as a purely psychological case, but is revealed to have a supernormal element.
There are some very striking moments in the film. The scattering of rose petals onto the bodies of the murdered girls is a striking motif, while various moments of female nudity aren't played for titillation the same way as in most Hammer films. Scenes of bloodletting the prone Elizabeth or watching the next victim get changed give an unpleasantly voyeuristic sensation. It makes the whole thing very disturbing. Overall, though, Sykes's direction is over the top and hard to follow. There's also a pretty unnecessary subplot with Michael Horden as a raving priest. It's a remarkable film, but ultimately too incoherent to really work.