"Strangers On A Train" bears many comparisons with Patricia Highsmith's other great work "The Talented Mr Ripley", in fact it can almost be seen as a precursor to it. Both introduce central characters that are incredibly dark and complex, and both show extreme obsession ending in murder. The character of Charles Bruno in this must surely rank as one of the greatest psychological profiles of a villain/misfit/outsider (take your pick) ever committed to paper, comparable with Graham Greene's portrayal of Pinky in "Brighton Rock", or Alex in Anthony Burgess's "A Clockwork Orange". We know he is a disturbed young man right from the outset, when he meets Guy on the train and indulges in a fatal and macabre "what if?" game with him. There is something almost Faustian about all this, as Guy gets drawn into a deadly game with someone who could almost be the Devil in human form.
As the book goes on and Guy gets himself deeper and deeper into Bruno's web, you find yourself asking if Guy is perhaps as innocent himself as he would like you to believe. That this isn't a simple case of a variation on the good twin/evil twin plot, but that Bruno is bringing out a dark side to Guy's character that he deep down wants to indulge. Bruno's own derangement, his alcohol-fuelled deleriums are disturbing, as is his infantile dependance on his awful mother, who wants to keep him forever as her spoilt little boy.
There are many classy touches to this book, including Bruno's seeming ability to be able to appear supernaturally inside locked rooms! And I can't see a fairground carousel anymore without thinking of Guy's wife and "The Girl With The Strawberry Curl", or whatever it was. There have been a few attempts to film this, (including a perfectly abominable t.v film in which Guy and Bruno's characters were done as women instead), but Alfred Hitchcock's is the only one worth seeing.