Joseph H. Lewis was one of the finest directors of film noir. This is surely his best.<br /><br />It doesn't have some of the standard features of what we now call film noir. Though American-made, it is set entirely in England. It lacks gangsters. It lacks a femme fatale. It does not lack crime.<br /><br />The title character answers an ad. She is overjoyed that she'll be making some money as a secretary. Instead, she wakes up days later as the pawn in a frightening plot. Only a very strong person could survive such a terrifyingly unsettling ordeal. And Nina Foch gives the sense of a strong woman as Julia.<br /><br />Part of the excitement comes from casting against type: Ms. Foch has an elegant manner. She is no screaming, cowering victim. She is actually a bit icy and patrician, albeit impecunious. This makes her character's plight all the more believable.<br /><br />Surely the single most fascinating element is the casting of Dame May Witty. She was (and is) probably most famous for the charming title character in "The Lady Vanishes." She has a sweet manner and a harmless, slightly dithering manner. But here she is far from a heroine.<br /><br />George Macready is excellent as her extremely troubled son. The whole cast, in fact, is superb.<br /><br />It seems that this famous and brilliant movie was made almost by accident. Undoubtedly the director knew exactly what he was doing. But he did it on a low budget. That is the thrill and charm of film noir, the real film noir: It is small, convincingly lowlife, and, in this case, unforgettable.