Victim 2117 by Jussi Adler-Olsen

Victim 2117 is the latest in the excellent Department Q series set in Denmark. The story starts with a Syrian refugee's death in the Mediterranean. A Spanish reporter down on his luck decides to focus on the dead woman. And that action gets him trapped in a terrorist plot with roots in the Middle East. Which turns out to involve Department Q member Assad's nemesis. And this is where we learn about Assad's mysterious past and how he managed to acquire so many specialized skills.At the same time, Rose and Gordon of the department are trying to track down a young Danish man with homicide in his heart--without a lot of clues to go on. It is really quite the page-turner from start to finish.