A simple, haunting musical phrase whistled offscreen tells us that a young girl will be killed. "Who Is the Murderer?" pleads a nearby placard as serial killer Hans Beckert, played by Peter Lorre (Casablanca, The Maltese Falcon), closes in on little Elsie Beckmann. In his harrowing masterwork M, Fritz Lang (Metropolis, The Testament of Dr. Mabuse) merges trenchant social commentary with chilling suspense, creating a panorama of private madness and public hysteria that to this day remains the blueprint for the psychological thriller.