Hitchcock’s Strangers On A Train starts with a brilliant conceit, and the film’s genius is in the way it resolves that question. Tennis player Guy Haines meets wealthy mamma’s boy Bruno Anthony on a rail journey, and the latter mentions an idea he’s had. Wouldn’t it be a wheeze if Bruno were to kill Guy’s troublesome ex-wife, freeing him up to marry his girlfriend, in return for Guy bumping off Bruno’s dad, whose tiresome insistence that Bruno work for a living is getting beyond a joke?

The clever bit here is the characterisation needed to make this fascinating notion into a compelling piece of cinema. Without engagement with the characters, this would be a mere intellectual exercise. But with a script by Raymond Chandler and Czenzi Ormonde, strong performances all round, and Hitchcock’s directorial flourishes, the story works a treat.

One of the issues is that it’s hard to be sympathetic to someone who gets involved with such a twisted plan. And Guy doesn’t. It’s the clearly deranged Bruno who ups the ante by strangling Guy’s missus, who we don’t miss too much once it’s established that she’s a nasty piece of work. Bruno then confronts Guy and demands that he do his part of the bargain, and do away with the paterfamilias of the Anthony household.

So, from being two people apparently equally complicit in a sick notion, Guy emerges as an honourable protagonist who now has to extract himself from a hellish situation. And Bruno is there at every turn, insisting on Guy’s half of a bargain that only ever existed in Bruno’s mind. It doesn’t help that Guy’s girlfriend realises Bruno is up to no good, and that her sister reminds Bruno of Guy’s ex wife. Bruno stares at the lookalike while he feigns strangling a society matron at an upmarket party, and she’s every bit aware of whose neck his hands would rather be around.

Fortunately Guy’s girlfriend is a good sort, and wanting to protect beau and sister alike she supports Guy in working against the dastardly Bruno. The devices used make for superb cinema: Guy has to beat a tennis opponent in record time to stand a chance of getting to Bruno, in a scene which demonstrates pace, tension, and character in unity. The showdown is in the fair where Bruno offed Guy’s ex, where he’s hoping to plant Guy’s lighter and implicate him in the murder. We’ve already seen Bruno nearly lose the lighter down a drain in cutaways from the tennis match, in a way that makes it clear just how few marbles Bruno has. The climactic scene happens aboard a merry-go-round, the two men duking it out as the carousel careers out of control and spins ever faster, putting children in peril and giving Guy a chance to establish his purity beyond doubt by rescuing a young boy.

How will the carousel be stopped? Fortunately an old carny hand is there to crawl under the mechanism, and the contrast between his painfully slow progress and the seemingly speed limit busting horses on top maximises tension just when it’s needed. The old guy stops the carousel, which breaks up and causes chaos. In the wreckage, Bruno is dying – and still trying to pin the murder on Guy. But good triumphs, when Bruno karks it to reveal Guy’s lighter in his hand, proving the latter’s innocence.

It’s classy stuff from start to finish, and a good reminder why Hitchcock continues to be rated as one of cinema’s leading practitioners. And I have another five of his films to watch in the boxset I recently acquired, so expect more reports to come.