Great line from the film: "Welcome to Tennessee...patron state of shootin' stuff."
Mark Wahlberg is a backwoods retired "Gunny" that was left behind for dead on his last covert mission. Now he just wants to be left alone, but the government wants to tap him for just one more job. A job that he is the only man qualified to do, which makes him the perfect candidate.
...and the perfect target.
He is double crossed and that don't set well with him.
The guy's name is Bob Lee Swagger for garsh sakes so suspend your disbelief for two hours and four minutes and this is a solid movie.