The short voice-over prologue is hokey, the pacing is stagnant, the script spells out, repeatedly, what exactly a sadist is, and Arch Hall's "now I'm being mean" look is often laughable. In spite of all that, the film does have some really tense situations and suspenseful chases, and is quite violent by 1963 standards. Manning is excellent as the psycho's silent, completely amoral girlfriend. (**1/2)