Simple and well acted, it has tension enough to knot the stomach.

As somebody who had not heard any of this before, it became a curious phenomenon to sit and watch a film and slowly have the realities begin to click into place.

This is a must-see and one of the best documentaries - and films - of this year.

I think this is a new genre that they're all sort of working their way through it and haven't got all the kinks worked out yet but it's a genre that works for me.