Dying light / Stuart MacBride.

Enhanced descriptions from Syndetics:

Detective Sergeant Logan MacRae has been bumped to D.I. Roberta Steel's Screw-up Squad after a raid he led on a warehouse rumored to be full of stolen property ended with no arrests and one officer critically injured. The backstabbing, limelight-stealing, laziest D.I. on Aberdeen's police force, Steel's team is made up of the no-hopers, the most worthless or inexperienced members of the homicide department, and Logan will do anything to prove he doesn't belong there. Including working overtime on two baffling cases: the murder by arson of six people, and the beating to death of a prostitute down by the docks, not a high priority compared to the fire. At least not until another prostitute ends up dead.
Although both cases seem simple on the surface---turns out the fire's victims are part of a drug dealer's inner circle, and what fate is to be expected for working girls in Aberdeen's red-light district? --- in Stuart MacBride's hands, what's going on in this rainy Scottish city is bound to be much more complicated than it appears. A detailed authenticity combines with a dark Scottish sense of humor and a lively cast of characters in MacBride's unputdownable second novel, confirming his status as a rising star of crime fiction.