Reading PD James is always a joy and an educational experience. Her mastery of the language and her razor sharp observations about human conduct make it a learning experience. Which is why her novels are not simple whodunnit but more like why they did it.
Cover her face is about a murder in an English mansion house. The victim is a servant girl who dies hours after announcing her engagement to the young man of the house. It seems straightforward but then as Adam Dalgliesh delves into the investigation, it reveals many people and many motives.
I have to admit that somewhere in the middle, it began to get a bit tedious. James' novels are quite demanding as they examine motives, intentions and mental make up of characters. However, it is worth it, because it is difficult to predict the killer. She makes the reader slog through it and yet rewards the reader's patience by giving a great motive and an unsuspecting killer in the end.
That is what makes James' novels readable and enjoyable.
Cover her Face is a great example. Do try it.