The Mistress of Alderley, by Robert Barnard

Very good mystery. This was fun, it had a pretty classic set up, but with a very modern approach, and the characters were unusual enough to feel fresh. Caroline knows she is Marius' mistress, and that he will not divorce his wife, but she is sure that he has bought her Alderley House, and that they have a very special relationship. When Marius is murdered, however, Caroline learns that all he has told her has been lies, and the unraveling of the story was quite satisfying.