BOTTOM LINE: The last, the best, and the most painful in this series, and an amazingly effective tie-up of most of the long-running threads. Sigrid's life changes drastically, as she works on a convoluted case while mourning the loss of her beloved Oscar. Highly recommended, but NOT if this is your first exposure to Sigrid.
WARNING: Don't begin reading this if you're at all "down" or depressed! The initial pages are quite sad and heart-tugging.
When her lover Oscar Naumann is killed in a car accident, Sigrid Harald's grieving is long and strong. But he's left her his enormous estate, filled with his highly-valuable artworks, and many things need managing, not the least of which is arranging for a retrospective of his work. Sigrid slowly comes to grips with the changes in her life - that she is now loverless, a rich and somewhat famous woman, and that she has influence in the art world of NYC. She's become more comfortable in her skin since meeting Oscar, and his death helps propel her forward, with more personal confidence than she ever exhibited before. This enables her to go back to work and begin to pick up the pieces of her life.
When one of the curators involved in Oscar's retrospective is found murdered in Oscar's apartment, she is called in to work the case, and finds much skullduggery and incestuous turmoil ongoing in the art world. Many subplots concur in this plot, and all are wrapped up nicely by the end, but it's Sigrid's state of mind and interactions with others that provide the motive power in this novel.
IMO many of the reviewers here don't quite get the main point of this book - the central theme is of Oscar's death and its many - and varied - repercussions, with the murder mysteries being secondary. That's not to say that the mystery plot isn't good (it definitely is at least par for the series, and that's high praise), it's just that the novel doesn't really "work" for the reader unless you have invested in Sigrid's growth as both a human being and a detective over the previous books. Yes, I know most long-running series authors tell you (or maybe it's their publisher's "line", not theirs...) that each book in a series can stand alone, on its own, but that's often not true due to poor or disconnected, or incomplete information/writing. That's not the case here, though.
Maron is an excellent writer, and for a devoted fan like me, this novel was superb. Heart-breaking, but superb. And for me it simply does NOT "stand alone", and must be read in the context of Sigrid's entire life. Your mileage may differ...