Kind of a downer. Emily Blunt is pretty easy to look at, though, even when she's generally miserable and putting up with various sorts of abuse. Throughout the entire movie.
She plays an FBI agent who does field work in a kidnap rescue team. In the aftermath of a particularly grisly mission in Arizona, a CIA spook (played by Josh Brolin) recruits her into a special operation, one where (he promises) they will be going after the drug kingpins who perpetrated this Arizona atrocity. Also involved is a gloomy Hispanic played by Benicio Del Toro.
If you noticed the "CIA" reference above, you will have accurately guessed that things are not as they initially appear. Ms. Blunt is perplexed, as her law-enforcement instincts are thwarted at every turn. She finds herself in mortal danger, and not just from the bad guys.
Arty (Oscar-nominated) cinematography. Ms. Blunt also handles an American accent well. Without going into spoilers, the plot's assumptions about the moral depravity of Our Side strains credulity. At one point, when confronted with his barbaric ways, one of the Bad Guys disclaims something much like one of the anti-drug commercials from the good old days: "I learned it by watching you!"