There are two novels fighting for dominance within the covers of Innocent Blood. One of them is rooted—just—in the everyday world; the other capers about in that no man's land to which Agatha Christie, Margery Allingham, and Dorothy L. Sayers made such frequent excursions. The former conveys something of the messiness involved in being human; the latter looks at crime through a dusty lorgnette. For most of the book, the two go their separate ways, but every so often they merge—with embarrassing consequences.

Of that trio who flourished in what Julian Symons has called "the golden age of the detective story", it is Dorothy L. Sayers who has exerted the strongest influence on the work of P. D. James. Sayers—the lady responsible for decking out Western civilization's sublimest poet in the sensible tweeds of an English gentleman—was a scholar, as her fiction constantly...