Sandman

Lars Kepler, the pseudonym for husband-and-wife team of Alexandra and Alexander Ahndoril, has written 7 novels in the "DS Joona Linna" series of Scandinavian noir, but this 4th installment is the first one I've read. I will refer you to the Washington Post's review for a succinct plot summary. Let it suffice to say that it is indeed very dark, and often grisly. It has to do with a serial killer, Jurek Walter, who, even though he is now in prison, is able to exert his evil influence on people outside, making them disappear or die terrible deaths. The action is precipitated when one of his victims, Mikael Kohler-Frost, makes an appearance after having been given up for dead 13 years ago. However, Mikael's sister, Felicia, is still missing and Joona is convinced that Walter knows where she is. Joona's colleague, Saga Bauer,  is sent onto the maximum security psych ward where Walter is being held to try and ascertain Felicia's whereabouts. Saga's experience on the ward create a sense of dread. There are all kinds of evil.
I think I got hooked on Scandinavian noir with Smilla's Sense of Snow (remember Gabriel Byrne in the film version?!) and I still regularly pick it up (see posts for Holt, Jansson, Jungstedt, and of course, Larsson), although, sometimes after reading one, I feel like I need to read something REALLY light and fluffy. Anyway, if you are a fan of the genre, you won't be disappointed here. Additional reviews from Kirkus, the New York Journal of Books, the Washington Times,  The New York Times and Publishers Weekly.