This is a truly riveting movie.  Peter Lorre looks like a psychotic cartoon character, and portrays a pedophile/murderer hiding out in a German City.  The police force is becoming more and more desperate, taking more and more rights from their citizens in order to catch the murderer.  With that huge police presence, the underworld becomes more agitated and tries to track him down as well so their will be some relief.  Just a great procedural with that whole Nazithing hanging over the head of filmmaker Fritz Lang.  Totally resonates today with the whole concept of what rights we are willing to give up to feel safe.  Not bad for a movie that is 78 years old.