Like Shadow of a Doubt, Strangers on a Train is a portrait of the doppelgänger, the double, as a shark in the murky waters of innocence and guilt. In 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, coauthored by Raymond Chandler from Patricia Highsmith's novel, 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 Hitchcock is Bruno's doppelgänger.