[P. D.] James's Death of an Expert Witness is quite possibly her best book: certainly the characters are the most credible, the writing is the most controlled (after a slight lapse in The Black Tower), and the sense of rhythm is the most subtle. There is an unexplained red herring early on and the reader is told a little too clearly that the solution is buried in the past, in a scene in which a scientific officer examines a coerolith, the skeleton of a microorganism from ancient seas now found in the...