Under the Copper Moon

I am about 6,000 words into the third book in the Cooper Mystery/Crime fiction series. Cooper has recovered from his last case involving the kidnapping of a Russian girl. He hasn't made much progress in finding his son Maxie. He plans to spend more time looking for him. It's been 7 years since his son disappeared and the trail has turned cold, no bitter cold. But an old witness comes up with a new clue that may finally lead Cooper to his son.