City of the Sun By David Levien

Very intense and powerful novel about the disappearance of a young boy, the trauma of his parents , the efforts to find the boy, and the changes in the lives of the parents.
After 14 months, the police still consider the boy to be a run away. The parents hire a former cop turned private detective, Frank Behr. Frank is carrying his own personal baggage in that feels responsible for the accidental death of his own son. Routine investigation and some luck leads the parents and the detective into danger and the unsavory world of child abuse and the sale of children.
The bad guys were very real and very frightening. This was a tough story.