Mark Wahlberg plays "Bob Lee Swagger", a deadly sniper; in the opening scene, set in Ethiopia, his spotter buddy shows him a picture of The Girl Back Home, unaware this is just about as fatal as wearing a red shirt on a Star Trek landing party. Quickly, Bobby Lee is being double-crossed by his superiors, and he barely makes it out alive.
But before you can get through a single verse of "Won't Get Fooled Again", Bobby Lee is fooled again, roped into an assassination plot, set up as a patsy. The remainder of the movie follows his quest, against astronomical odds, to clear himself and extract revenge.
On its face, this is a competent thriller; but the plot presumes a secret sees-all knows-all oil-cabal conspiracy permeating the highest levels of the US government, which doesn't have the slightest cavil about committing murders large and small in quest of its evil capitalist goals. You can't read Bill Whittle without feeling major disgust for this sort of diseased plot device, feeding the snakes-in-the-brain paranoia of a small but significant segment of the populace.