The Chinese Proverb. Hunter Grant series, #1

Army veteran Hunter Grant thought he had left war behind in Afghanistan - a conflict that left him with physical and psychological scars. But finding an unconscious girl in the Northland bush and gradually untangling her story involves him in a war of a different kind in his own country. Hunter sets out to find and punish the man Dao calls Master, but he soon finds there is more to this story than enslavement.
Before long he himself is being hunted by the overlord of a drug empire whose sole objective is to kill Dao because she knows too much. Protecting her and waging war while trying to keep the police from stifling his enterprise takes all Hunter's ingenuity and determination and puts him in deadly jeopardy.