Unimaginable horror brought to the screen.

The phone call was the last the young woman ever made: "I just wanted to tell you I love you. We're having a little trouble with the plane." She was aboard United Airways Flight 93, one of the aircraft hijacked in the September 11 terrorist attacks on the US.

With the TV schedules crowded with programmes marking the first anniversary of 9/11, this Tonight With Trevor McDonald special attempts something different.

The only real footage is glimpsed occasionally on TV sets in the background. Rather than turn the story into a Hollywood-style movie, this drama-documentary opts to use interviews with relatives of those aboard interwoven with reconstructions of events on the plane.

There's still something slightly surreal about this, in much the same way that watching the Twin Towers collapse live on TV seemed like a scene from a disaster movie. You simply can't believe it's happening

On Flight 93, we witness passengers boarding the plane and then the sudden, violent seizing of the aircraft in mid-flight by three terrorists.

Passengers were confined to the rear of the plane as the hijackers took over the flight controls. As some passengers plot to seize back control from the hijackers, others contact loved ones on their mobile phones.

One man and his wife spend the time saying "I love you" back and forth, over and over again. Another tells his wife to call the authorities. A terrified girl is comforted over the phone by her mother, who is determined not to give in to her feelings. "I wanted to be unselfish and not end up a crying, clinging mother," she explains.

When passengers hear about the other attacks, at the World Trade Centre and the Pentagon, they realise their hijackers too are on a suicide mission. They determine to take back the aeroplane, armed with whatever they can find in the galley and use as weapons.

With a cry of "Let's roll", they storm the cockpit. Moments later Flight 93 plunges to the ground in a field in Pennsylvania, killing all 44 people on board. The passengers' heroic actions were not in vain as the fourth target, widely believed to be the White House, was saved.

This programme is a worthy memorial to those aboard and, like last week's C5 documentary The Firefighters' Story, all the more effective for letting the people affected tell the tale.