M is for Murderer; also for Masterpiece. Lang’s first and greatest sound film concerns the hunt for a child-killer in a German city, and his depiction of a community gripped by fear is a master-class in the suggestive use of shadow, smoke, sound and off-screen space to create an atmosphere of tension and terror. There is an element of grotesque comedy also, as the city’s underworld joins in the investigation: the killer is proving bad for business. When the wretched creature is cornered in a deserted warehouse and tried by a kangaroo court, Peter Lorre’s characterisation comes into its own: this is one of the unforgettable performances of the screen. ‘Those marble pupils’, wrote Graham Greene about Lorre at the time, ‘are like the eye-piece of a microscope through which you see the tangled mind laid flat: love and lust, nobility and perversity, hatred of itself and despair jump out at you.’