A neat little Belgian-Italian horror flick brimming with atmosphere. Complete with a kinky wardrobe, Erika Blanc is perfect as Lisa Miller, the succubus. She displays supreme sensuality in her "normal" guise, then transforms into a murderous demon with such face-pulling, over-the-top relish that your skin will crawl. If she's not enough, Daniel Emilfork is on hand to complete things as a corpselike vision of the devil. The deaths are creative and brutal, the Gothic castle is very creepy, and the ending has a shock-twist that you'll never see coming. Julie sings the haunting theme song, which will stick with you long after the picture is over. The only debit is the moralizing angle, which is faintly offensive, but can be overlooked in light of everything else. Very well done on a small budget and beautifully photographed in wonderfully cheap, grainy color.
I saw this movie on videotape under the title Succubus. This tape is an absolute mess--videoburned title, scenes trimmed, scenes out of order toward the end--and should be avoided. It turns a fun, entertaining Euro-horror into a throughly frustrating experience.
Trivia: Though it was released in Europe in 1971, this film did not hit the U.S. until 1974, when Hemisphere released it as Devil's Nightmare to coattail The Exorcist.