Phantom by Jo Nesbø

Inspector Harry Hole attempts to exonerate his would-be son Oleg in this installment of Jo Nesbø’s New York Times bestselling series.

When Harry Hole moved to Hong Kong, he thought he was escaping the traumas of his life in Oslo and his career as a detective for good. But now, the unthinkable has happened—Oleg, the boy he helped raise, has been arrested for killing a man. Harry can't believe that Oleg is a murderer, so he returns to hunt down the real killer.

Although he's off the police force, he still has a case to solve that will send him into the depths of the city’s drug culture, where a shockingly deadly new street drug is gaining popularity. This most personal of investigations will force Harry to confront his past and the wrenching truth about Oleg and himself.