An interesting idea - two men meet on a train and discover that they each have someone in their lives whom they want dead. They discuss the possibility of swapping murders, thus leaving no trace of themselves at the scene and allowing each of them to constuct an alibi. Ingenious.
But the real power of this book lies in Highsmith's exploration of a murderer's guilt. The minute but constant decay of a tortured psyche. The impact that the wrong decision can have on one man's life as it steadily unravels beyond his control.
At times this book is philosophical and questions the validty of good and evil co-existing in all men. But the plot is incredibly frustrating too - there are too many bad decisions made by the main protagonist that leave you incredulous. In this respect it reminded me of a Shakespearean tragedy, played out with Othello and Iago or Macbeth and Lady Macbeth. Tragedy is inevitable when a character allows his weaknesses to be exploited and Highsmith achieves this in a masterly way, never letting the tension ease, and one catasrophe and bad decision roll into another creating a demonic snowball of events.
There are moments of true genius in Strangers on a Train but I found it labourious to read at times, with too many peripheral characters and the main characters' actions were sometimes too frustrating and lacked genuine resolve. But I may be being too harsh. Strangers on a Train is a cut above your average thriller and contains many things worth thinking about. On another reading I may give five stars, as it is a book that needs to savoured and turned over in your mind, and not all crime/thrillers can be accused of such psychological depth.