A tennis player named “Haines” (Farley Granger) is riding in a train car when "Bruno" (Robert Walker) starts talking to him. At first, everything seems normal; Haines assumes this man is simply someone who wants some company while enjoying a drink. It doesn’t take long for it to become apparent that both men are unhappy with their current circumstances. “Haines” is married to “Miriam” (Kasey Rogers), but he longs to be with the senator's daughter "Anne" (Ruth Roman), and "Bruno" wants to get rid of his domineering father (Jonathan Hale). The two strangers then concoct a scheme, each planning a murder that would resolve the other’s issues. Haines isn't interested in participating, but when "Bruno" takes things into his own hands, threatening blackmail emerges, and the police begin investigating, putting “Haines” in an uncomfortable position. This is one of Raymond Chandler's more skillfully plotted stories, with a complex series of escalating dangers for the hapless, lovelorn, and inexperienced “Haines.” There’s a noticeable connection between Walker and Granger, who both keep the story engaging as Alfred Hitchcock steadily increases the pressure on these characters. The climax unfolds at a fairground, where bright lights, high-spirited music, and growing anxiety combine to create a tense drama with an impressive musical score (by Dimitri Tiomkin), exploring human flaws, deception, and recklessness. Trains are always effective settings for crime thrillers, and the film benefits from solid supporting performances by Marion Lorne, Leo G. Carroll, Hitchcock’s daughter Patricia as the intrusive “Barbara,” and a brief appearance by Norma Varden (before she started wearing those large hats) which adds depth—and distraction—to their plans. It might leave you hesitant to chat with anyone on your next train journey!

Source on TMDB