As is always the case with James, the history and back-story of the characters is very important, and becomes essential to solving the mystery. What's really kind of sad for me is that this appears to be the end of the Dalgliesh series. Dalgliesh is ready to retire from Scotland Yard, and his two junior associates are tying up their loose ends. In reading this I couldn't help but think that James's heart was more in writing her Scotland Yard characters than in producing an actual mystery. This one didn't live up to the level of depth or suspense of the earlier volumes in the series.
P.D. James, The Private Patient (Knopf, 2008) ISBN: 0307270777