Given the time this film was released (Europe was on the verge of being plunged into WWII), this film expertly uses the fear of the nation to create a large amount of suspense. Is this exploitation? Perhaps. But it seemed to captivate audiences of the time. On a side note, good luck finding a decent copy of this film; I've noticed the only companies to release this film are the public domain-type, Laserlight usually being the best, but even then, the prints are often times horrible at best and the sound is muffled and unintelligible. Oskar Homolka plays a
great bad guy - all menacing stares and slightly sinister accent. There's a scene of a bomb going off that is in question, and even Hitchcock has admitted regretting this particular scene, but as this is based on a novel, it remains true to the source material, so I give it props for not kowtowing to studio pressure for a "happier" means to an end, but again, it does seem a bit exploitative to use as a device of sympathy. All in all, one of Hitchcock's better early films, but as the Movie Guide review says below, a notch below other films of the era.