Long Lost, Harlan Coben

Brad Denning is a successful architect living a perfect life in Denver with his loving wife and son. Or so it would be, if not for the haunting memory of his brother Petey who disappeared while under Brad's supervision when they were kids. Now, a man claiming to be his sibling has mysteriously appeared and Brad is eager to take him in, despite the man's haggard appearance and reluctance to reveal anything about his past. "Petey" is a welcome addition to the family, until a camping trip goes terribly wrong and Brad returns home to find that his devoted wife and son have been abducted. Certain that Petey -- or whoever he may be -- is responsible for the horrible crime, Brad sets out to recover his family. Travelling alone through America's heartland, it's a race against time as Brad struggles to get to his family before the terrible secret of what really happened long ago destroys everything he cares about.