Over the years, a couple of thousand or more short stories and novels have featured apparently 'impossible crimes': they are listed in a marvellous reference work by Robert Adey. This specialised form of detective story requires a sure touch if it is not to misfire. By common consent, John Dickson Carr was the finest exponent of 'locked room murders' and his work indirectly inspired the hit television series 'Jonathan Creek'.
This novel is widely regarded as his finest achievement (although one might add that there are several worthy contenders in the Carr canon). It features Dr Gideon Fell, a Chestertonian figure who was perhaps his most compelling detective character. There are three 'impossible' puzzles here to savour, and even if the explanations occasionally depend over-much upon contrivance, the book remains an enjoyable read. A bonus for fans is the 'locked-room lecture' in chapter 17, in which Fell offers a learned classification of this type of mystery.