The fierceness of the human spirit & doing the right thing is demonstrated beautifully in Dar Salim's character Ahmed. His conviction to do anything necessary to get Gyllenhall's character John, some medical help - is amazing.
Ritchie pulls out all the stops as a slow-burn of frustration & meltdown congeals with flashbacks of the agony of trying to stay alive. I won't say anymore, except that the filming and acting is superb; and the background music is an emotion all its own.