Now, I am inclined to regard having-it-both-ways as one of the less admirable perversions, at any rate where drama is concerned. It worries me when a man exploits all the resources of the country-house thriller, with art and consummate cunning, and then rounds on me and rebukes me for having presumed to enjoy his efforts. How can he tell me that 'the detective story is the usual recreation of snobbish, outdated, life-hating, ignoble minds' when he plainly wants my outdated bum in his theatre seat, my ignoble money in his pocket, and my life-hating applause in his ears? Yet this was the message that rang out at the moral climax of Sleuth, and it is heard again, differently phrased, at the end of Murderer….

There are two main surprises [in Murderer], neither very surprising. There's also a lot of chat, mostly about murderers and murder, between Norman and...