After a hilarious built-in apologia from the producers (who took heat in Britain for implying that siblings of Mongoloids may be dangerous), this thriller about an English boarding-house beset with a psychopathic young man gets more and more ridiculous. I felt a little sorry for esteemed British actress Billie Whitelaw here (forced to come onto pasty-faced man-child Hywel Bennett as if he were a simpleton stud). Brighter aspects are a good performance by Hayley Mills as the pretty librarian who is befriended by Bennett; a weird, wonderful score by Bernard Herrmann; as well as some fancy camera tricks and editing. The picture is hard to locate, but is it worth the search? For Hayley Mills addicts, yes. All others looking for a good 1960s screamer, perhaps not. Director and co-scenarist Roy Boulting attempts to ape Hitchcock's style, which is not always wise if the material itself isn't up to par. Here, the convoluted script falls completely apart with 30 minutes left on the clock. **1/2 from ****