Friend of the Devil by Peter Robinson.
Peter is one of my favourite authors. He's such an amazing writer! Everytime I read one of his books I think it's his best one yet...and then I read the next one.
Friend of the Devil is told partly from Alan Banks' point of view and partly from Annie Cabot's point of view. Annie has been seconded to another division, yet somehow their cases manage to connect.
They are both damaged individuals, both fiercely independent, both very good detectives. A relationship between them didn't work, but both wonder about trying again.
Peter and I at Book 'Em Mysteries in Pasadena, June 2006
Yes, I'm discussing the characters rather than the plot. There is definitely a plot; in fact, there are two of them. But Peter's characters, even the minor ones, are very well drawn. His characterizations are just one of the reasons his writing is so enjoyable to read.
I couldn't believe this is the seventeenth Inspector Banks book. I hope he continues writing them for a long time.