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.

While it doesn't offer any answers, it both thrills and makes you think.

It is an exhilarating, distressing, funny and profound film, with one of the more memorable film scores in years,