Bloody Sunday director Paul Greengrass marks the five-year anniversary on the September 11, 2001, terrorist attacks on the United States with this speculative meditation on the events that took place onboard the fourth hijacked plane, and the actions of the passengers who gave their lives to ensure the safety of others. Told in real time and acted out by a cast of unknowns who were provided with detailed studies of their real-life counterparts, United 93 attempts to reconstruct the airborne tragedy from the view of the ground and flight controllers, the passengers, and their nervous families awaiting word on the fate of their loved ones. As the terrified travelers and crew gradually become aware of the historical events taking place on the ground so far beneath them, the 90 minutes in which a random collection of strangers realized their fate and came together to confront an unthinkable threat are re-created.