The American government team sent to "investigate" the crime scene goes without proper authority, but in a fit of emotional fervor the leader puts together a team committed to bringing a kind of justice to a fallen friend and comrade. The story depicts experienced and maybe "smarter," self-assured American investigators jumping into the "crime scene" evidently oblivious to the culture, and even cavalier regarding it. Acting as if the Americans have a thing or two to teach the Saudis about how to run a proper investigation, they are constantly frustrated and their progress is blocked for religious, cultural, and political reasons they never grasp.
The movie's climax ends with a dramatic chase and shoot out among the terrorist group in the city, including women and children (used as manipulative pawns). Without giving too much away, one of the last things we see is the patriarch master-mind passing on his legacy to a grand child close by him in his dying breath. In essence, he tells his kid to never stop killing the Americans until they're obliterated. The movie ends, though it was never intended to end this way, and the tragedy of children involved in violence and wars much bigger than them and ones they don't understand is perpetuated.
This ending reminded me of the brilliant opening of Lord of War. This portion of the movie has ironically been called "The Life of a Bullet." Ironic, because the sole intent of a bullet is to squash life. Follow the path of a bullet from a Russian manufacturing plant, into the Russian military, then eventually handed over into corrupt hands.