The Keeper of Lost Causes, by Jussi Adler-Olsen, is the first of the department Q series. Department Q is tasked with reviewing cold case files to see if there is anything new that can be found. In the initial case, an attractive politician disappears on a ferry.
The main investigator, Carl Morck, is dealing with the trauma of having been shot but surviving while one of his partners was killed and a second was permanently disabled. And, the shooter wasn’t caught. Carl deals with his anger and lack of motivation while learning to work with a new assistant, a Muslim immigrant, who seems kind and caring on the surface, but shows a tougher, resilient and insightful side as they move through the cold path.
The characters are distinct and they are flawed as they work through their own personal demons. They are relatable and real, not in any way cartoonish.