The film review on bbc news. To take us through the cinema releases, as ever, mark kermode. What have you been watching this week . A very big week, obviously. We have dunkirk, the new Christopher Nolan film, about which everybody is talking. We have city of ghosts, a very harrowing documentary from the maker of cartel land. And Captain Underpants the epic first movie, which is really funny. Everyone is talking about dunkirk. The scale and ambition of this is remarkable. It is and also the ambition of the release. It is the story of dunkirk told by Christopher Nolan who has made things like dark knight, interstellar and inception, and it is the story of the evacuation told through Three Intertwining Strands that loosely follow land, sea and air. But although the story itself is fairly straightforward, it is told over three different timescales, one of the stories lasts one week, one of the stories lasts one day, one lasts one hour and these strands. If you know anything at all about no