The Troubled Man by Henning Mankell
When a retired high-ranking naval officer vanishes one day in a forest near Stockholm, troubled detective Kurt Wallander takes it upon himself to investigate his disappearance.
Although the disappearance has nothing to do with Wallander officially, the vanished man is the future father-in-law of his daughter Linda. Soon, Wallander uncovers ties back to Cold War espionage and is forced to confront his own troubled reality as he continues to investigate the baffling case.
The tenth and final book in Henning Mankell's Wallander series, this novel brings to a close the detective's last case in a gripping finale.