If setting this dystopian drama in the 1970s is slightly puzzling, then it’s a detail in a film which builds effectively before snapping and ratcheting the tension and the incidents. By no means a comfortable watch, this is a blatant and not-so-subtle piece, but one which really gets its hooks in and lays on an effective moral story. Some comic moments and some which are stark, though overall, this is a hugely effective, watchable movie.