The Runaway by Nick Petrie

While driving across the country, Peter Ash encounters a young pregnant woman named Helene in northern Nebraska. Her car has broken down and she's trying to escape her husband, Roy, who will not let her go. Peter feels an obligation to help Helene get free of Roy, no matter the consequences. The Runaway is the latest book in the Peter Ash series and is a great read-alike for Lee Child and Thomas Perry.