The Keeper of Lost Causes by Jussi Adler-Olsen
If you liked the Girl with the Dragon Tattoo series, then this one is your cup of tea, minus some of the stomach-churning sex crimes and alternative lifestyles from Girl.  Set in Copenhagen, Carl Mork is a cranky, embittered Danish policeman, whose partner has been paralyzed, his other partner killed, and bad publicity in the newspapers for a drug bust gone bad.  So, of course, his incompetent and unethical superiors create a new job for Carl, head of the new Department Q, in charge of 'lost cause cases.' Carl and his mysterious Syrian sidekick begin to investigate the disappearance five years ago, of a popular politician.  As we find out more about her accident and her family background, we are sucked into the search for the truth, just as Carl is.  Well written, amusing at times, and thoughtful segues between the past and the present, the Department Q books are on my list as future books to read, especially for those of us who love a good mystery.