This British thriller benefits from a solid she versus she conflict between wonderfully evil Jean Kent and empathy-inducing threatened damsel Mona Freeman, but the screenplay piles on way too obvious details, events and behavior under the guise of "suspense". Other than one quality red herring (the ambiguous hero playing Mona's doctor/boyfriend), the movie plays on a single note: the heroine's growing paranoia is anything but that -she's being constantly set up to be Jean's next victim.

Kent's acting is only matched on film by such greats as Dame Judith Anderson, who had the same uncanny ability to appear placid and even perfectly reasonable on the surface, while hiding malevolence under the surface. The movie would have been far more successful had there been some possiblity that Mona's character was imagining things, rather than spoon feeding the viewer a constant stream of evidence that her suppositions are all true. The story's final twist and instant happy ending don't ring true at all.