This is an extremely accomplished and upsetting documentary that, in a better world, would not need to exist. . . . Derki's film is an amazing feat of staying calm in circumstances where I personally would be just praying to survive, let alone having the fortitude to think about framing — the distance between the camera and a gun/mine is often alarmingly close, and even though the director was there and obviously intact to introduce the film, it'll make you sweat.