Absolutely brilliant. I'd never read P.D. James before, though I know her reputation among mystery buffs is unimpeachable, and of course I've seen the film adaptation, which I like very much.
As seen through the eyes of historian and former Oxford don Theo Faren -- "former" because the only educational efforts now are soft courses which keep the population entertained -- it's a world of moral greys, which gradually turn, for him, into black-and-whites when he is approached for help by a former student who is, miraculously, pregnant.
The tale that follows is a subtle morality play, beautifully written and realized. Unlike the film, which has been recast in a more gritty, depressing and obviously "dystopian" light, James's novel, though containing horrors aplenty, also revels in the beauty of an English countryside gone back to nature, focuses on the moral considerations of what it means to be human . . . and holds out the hope that there will always be those among us who will choose the right path rather than the easy one.