DCI Carl Morck is a brilliant cop whose razor-sharp sarcasm has made him no friends in the Edinburgh police department. When a shooting leaves a young pc dead and his partner paralyzed, Carl finds himself exiled to the basement as the sole member of Department Q, a newly formed cold case unit.

The department is a PR stunt meant to distract the public from the failures of an under-resourced police force that is glad to see the back of him. But more by accident than design, Carl begins building a gang of waifs and strays who have everything to prove.

When the stone-cold trail of a prominent civil servant who disappeared several years ago starts to heat up, Carl is back doing what he does best - rattling cages and refusing to take no for an answer.