The Hitchcock noirs (see also Shadow of a Doubt, May 14) are all portraits of the Döppleganger, the Double, as a shark in the murky waters of innocence and guilt. In Strangers on a Train, Hitchcock's most Faustian treatment of the transference of guilt, Robert Walker plays the psychopathic sprite Bruno, who empathically makes himself the agent for Farley Granger's unannounced desire to murder his wife. The screenplay, co-authored by Raymond Chandler, serves up Walker's style of smirky innuendo on a silver tray, while cinematographer Robert Burks helps Hitchcock turn authentic sites (Washington, the record shop, the traveling fair, the train) into an ingeniously linked series of set-pieces and visual puns. In no other Hitchcock film is sexuality so obsessively suffused with black humor; we know that Hitch is Bruno's Döppleganger.