In this sixth book in the series Police Inspector Harry Hole investigates a number of disappearances/murders in Norway - which he suspects is the work of a serial killer. Over about twenty years a number of women have disappeared, and one is known dead. In each case the woman is married and a mother. In a bizarre twist, a snowman has been left at the site of each disappearance, in one case wearing the pink scarf and containing the cell phone of the victim. This and an anonymous note sent to Harry lead to the killer being dubbed "The Snowman."
Harry and his new partner Katrine Bratt, along with a small task force, are assigned to the case. When Harry and his team uncover a connection among the women a number of possible suspects come to light - one after another - each seeming to have a possible motive. Meanwhile, Harry struggles with his alcoholism while the love of his life, Rakel, prepares to move in with another man. On the lighter side Harry takes time to maintain his bond with Rakel's son Oleg and deals with a mold exterminator who dismantles his apartment.
The characters in the story are well-developed, interesting, and often quirky and there are plenty of twists and turns. The book races along to a dramatic climax - where the murderer plans to stage a grande finale. A compelling, well-written thriller, highly recommended.