This is quite a decent little conspiracy mystery. "Cynthia" (Jean Lodge) is the eponymous heiress who has been living in the care of her controlling, wheelchair-bound, step-father "Kimber" (Philip Leaver - reminded me a little of Francis L. Sullivan). When she announces that she wishes to marry; he has to act and she promptly disappears. Her friend "Miss. Frayne" (Julia Lang) goes to investigate and puzzled by all of this, summons her employer - the hypnotist "Dr. Morelle" (Valentine Dyall) to get to the bottom of everything... It's a fairly routine mystery, and as it is told via retrospective we have little jeopardy - but it is still quite enjoyable to watch Lyall in full pomp and there are, as usual, some lovely scenes from Hugh Griffiths as the amiable, but scatty butler "Bensall". It's very much of it's time, this film - there is a condescension from Lyall to Lang that's over-egged a bit, but it doesn't spoil it too much - it's just a quickly paced, sometimes humorous, crime thriller that easily kills an hour - without killing anything else!
