Strangers On a Train is one of the best Hitchcock movies - and best movies - ever made.
The plot is super simple: two men meet by accident on a train. Guy Haines (Farley Granger) is a famous tennis player and is recognized by Bruno Anthony (Robert Walker), a aging ne'er do well. Bruno tells Guy about his father who is always complaining about the money that Bruno spends. Bruno reads the gossip columns so he knows that Guy wants to marry a Senator's daughter but his cheating wife won't give him a divorce. Bruno suggests that they 'swap' murders. That way, the police will never figure it out because there will be no motive.
Unbeknownst to Guy, Bruno thinks they have made a deal and kills Guy's wife. The scene in which he strangles her as seen through her broken eyeglasses which have fallen to the ground is every bit as chilling as a certain shower scene Hitchcock shot about a decade later.
Bruno then goes to Guy and expects him to reciprocate. Robert Walker should have won an Oscar just for the way he said, "Guy" as he calls on Haines so that he could give Guy the keys to his father's house and details on where his father's bedroom is.
When it becomes clear that Guy does not intend to murder Bruno's father, Bruno decides to plant a cigarette lighter that belongs to Guy at the murder scene of Guy's wife, framing Guy for the murder.
The cast is top notch from the two leads down to the two detectives (Robert Gist and John Douchette) who are tailing Haines to try to pin his wife's murder on him. The music by Dimitri Tiomkin is perfect.
But the BIG story of Strangers is that the screenplay is by Raymond Chandler, among others. There are many elements of Chandler's best work in this screenplay. The story is told almost exclusively from Haines' perspective, just as Chandler's Marlowe books are. His first screenplay was a gem, Double Indemnity. He did not like working for Hollywood because, as is still the case, the writer is just an employee of the studio and the studio or director or even the actor can make changes to the script. Chandler did not like anyone changing even a comma - so there were lots of conflicts. And there were also a few of the best film noir films ever made.