For me this is possibly the best book in the Harry Hole series. It opens in Hong Kong where Harry is taking some time away after the end of the Snowman case. Shortly after Kaja Solness appears to bring Harry back as his help is needed in a serial killer case. Only when it is revealed that Harry's father is critically ill in hospital does he agree to accompany her home.
For me the great strength of this book was the real development of characters. Harry Hole seems to be a more rounded character now especially following interactions with his father that we are witness to. Other characters who were introduced seemed to be given very clear personalities. I think the main weakness with the book was that it was a little bit too long. At times some of the narrative could have been trimmed.
I would definitely recommend reading the books in the correct order as there are references to the snowman amongst other previous cases