The Good Girl by Mary Kubica

Colin Thatcher didn't seem like a dangerous one-night stand, and even though it was a rash choice on Mia Dennett's end she didn't think it would end with her being kidnapped—then it's too late to go back so Colin hides Mia in a concealed cabin instead of delivering her to his employers, as her mother and Detective Gabe Hoffman stop at nothing to find her. No one ever anticipated the bonds that came, though.