American Drifter by Heather Graham and Chad Michael Murray

River is a man at odds with himself.  He is a tough loner trying to forget all the horrible things that come from too many years at war yet willing to risk everything to save an abused dog.  Brazil seemed like the perfect place to hide - loud, beautiful and unlike anything he knew but then he met the beautiful and free spirited Natal and his life was changed.  His nightmares now include her relationship with a drug kingpin the terror of Rio.  She is good for him pulling him out of dark moods but can he keep the girl and keep his life?  For fans of Jack Reacher this is one solid action packed thriller starring a hero with a heart of gold.