Acclaimed filmmaker Paul Greengrass ("Bloody Sunday," "The Bourne Supremacy") writes and directs an unflinching drama that tells the story of the passengers and crew, their families on the ground and the flight controllers who watched in dawning horror as United Airlines Flight 93 became the fourth hijacked plane on the day of the worst terrorist attacks on American soil: September 11, 2001.

"United 93" recreates the doomed trip in actual time, from takeoff to hijacking to the realization by those onboard that their plane was part of a coordinated attack unfolding on the ground beneath them. The film attempts to understand the abject fear and courageous decisions of those who-over the course of just 90 minutes-transformed from a random assembly of disconnected strangers into bonded allies who confronted an unthinkable situation.

As 2006 marks the passing of five years since the epochal events of 9/11, the time has come for contemporary cinema's leading filmmakers to dramatically investigate the events of that day, its causes and its consequences, and the everyday individuals whose fates were forever altered while simply going about their common workday rituals.

Greengrass, known for films such as "Resurrected" and "Bloody Sunday," brings to "United 93" a history of compassionate filmmaking that has explored some of the most troubled incidents of recent world history-when politics turns to violence, when beliefs slip into zealotry. As there is no perfect record of the hijacking's exact details and hostage retaliation, Greengrass takes a careful hand and partially improvises the events with an ensemble cast of unknown actors who were given studies of their United 93 counterparts.

"United 93" intends to dignify the memory of those on that flight, the men and women whose sacrifice remains one of the most heroic legacies of the incomprehensible tragedies that unfolded on that autumn morning.