Paul Greengrass delivers a relentless real time account of the events on board United 93. Using unknown actors and a documentary style adds to the raw emotions the film depicts. Showing the best and worst of humanity without descending into over-sentimentality or preachy moments. It is a film you endure rather than enjoy. But it is a powerfully haunting film that acts both as a respectful memorial to these passengers and an solid exercise in thought provoking cinema.