I believe Greengrass is thoroughly acquainted with the facts in Bloody Sunday but I still felt starved if not for information then for an analytical model. On the other hand, this puts Bloody Sunday in the league of Costa-Gavras's Z (1969), another streamlined jolt of then-recent political history. Z has a more varied style than Bloody Sunday, but there's nothing casual about it. Its view of history is locked and loaded and aimed point blank at your face. By contrast, Bloody Sunday includes one brief sequence of impressive offhand mastery, in which Ivan Cooper and his girlfriend try to carry on a tense personal discussion at headquarters while constantly getting interrupted by other people and phone calls. (And remember, Costa-Gavras had no qualms about making one of his villains a psychotic homo.)

Greengrass finds his groove in the middle of turbulence, but he needs to hop out before his groove becomes a rut. His work in Bloody Sunday and United 93 is impressive but finally too flashy and pointed, and yet unstructured, to have the tragic dimension they sorely need. In the scenes dealing with the air traffic controllers in United 93 you become aware of how large the skies are when the terrorists turn off the airplanes' transponders and the big birds disappear from the radar. (It takes the controllers a while to realize that the missing American Airlines flight 11 must have gone into the smoking hole in the World Trade Center's north tower.) In United 93 the action takes place in the skies, but that's all the action going on in them. There's certainly no mystery on the other side of them. The events are no more freed from the flow of historic time for contemplation, or sorrow, or consolation than in an action movie. There's just shock, relived, like a nightmare duped onto a replayable cartridge.