"Snitch" borrows those facts and takes them for a nice walk - Johnson is John Matthews, a trucking-company owner whose son is jailed for a one-time ecstasy deal, held without bail and brutalized in prison, where he's staring at a 10-year minimum sentence, despite it being his first offense.
Matthews is in a second marriage, somewhat estranged from the boy, and on shaky ground with his ex (Melina Kanakaredes), but immediately and desperately tries to get his son out. This means making a deal with a grandstanding prosecutor (Susan Sarandon) to free his son by going after the dealers on his own.
Here Johnson goes interestingly against type - he's a suburban businessman out of his depth, and ends up bloodied and embarrassed in his first attempt at infiltration. So he enlists the help of an ex-con employee (Jon Bernthal, excellent), whose introduction to a local dealer (Michael Kenneth Williams from "The Wire") leads to an encounter with a high-level Mexican cartel boss (Benjamin Bratt).
The movie is directed by Ric Roman Waugh, a former stuntman, and it feels like something made by a fellow from the tough-guy end of the business. It is comfortable in Matthews' world of trucks and interstates and loading docks, and has throwback masculinity. This means, by the way, that Johnson and Bernthal register most strongly as fathers, rather than action figures. (You can see why Waugh has been tapped to direct the upcoming movie about the Horizon deepwater oil-rig disaster).
What makes this role so different for Johnson is the way his character registers sweaty fear at being in over his head - the script consistently undercuts expectations that the former wrestler will erupt in a spasm of cartoon ass-kicking. He's vulnerable here and, as such, attracts the sympathy of a DEA agent (Barry Pepper).
And the movie has nice touches - glossy wide-screen presentation, though a bit heavy on the hand-held. Gorgeous, effective music. And Waugh does show his roots - when cars do blow up, they blow up real good.