KEITH WAS IN HIS OFFICE IN the World Trade Centre when the first aircraft hit. He tried to save his friend Rumsey, but Rumsey died even as Keith pulled him from the swivel chair under the collapsed ceiling.

Keith walked down the stairs in the slow mass of numbly moving survivors, engulfed in smoke and dust. When he reached the street he kept walking, carrying someone else’s briefcase, passed to him in the confusion. Later a plumber’s van picked him up and he gave his former wife’s address, and the van carried him there.

She, Lianne, was shocked by his bloodied appearance, the glass embedded in his face, his left arm hanging uselessly at his side. She telephoned 911 but the lines were constantly busy, so they walked ten blocks to the nearest hospital, and Keith was kept in overnight.

Justin, Keith and Lianne’s seven-year-old son, began to watch the skies. He and two friends did it together, at the window on the 27th floor of the friends’ apartment building. He took Keith’s binoculars, without permission, to watch for aeroplanes. They heard that a man called Bill Lawton was going to come back with more aircraft. Justin did not believe that the towers had come down; he was convinced that Bill Lawton – Bin Laden – would make the towers come down next time.

Don DeLillo’s novel is about trauma. And not just any trauma, but a world-changing one. How the world was changed by it is left unsaid – there is one tangential mention: three years after the event, DeLillo lightly sketches a moment in an antiwar march on which Lianne has taken Justin.

Otherwise the universal is focused in the particular here, explaining through a handful of affected lives why the trauma was so deep. The novel makes the point – a point so obvious that we need to be reminded of it repeatedly because its obviousness renders it invisible – that survivors suffer more, and for longer, than the dead.

It also reminds us how oddly people behave when in shock. For example, Lianne becomes obsessed with the Middle-Eastern music emanating ceaselessly from a neighbour’s flat, eventually hitting the woman who plays it. Keith has a brief affair with Florence, the woman whose briefcase he carried from the collapsing tower, because only Florence, who walked down the dark stairs in the smoke with the same crowds, could understand what it had been like.

When Keith’s affair with Florence is over he gives up work to become a full-time poker player, travelling to Nevada and Atlantic City and anywhere that big-stakes games are played. He used to play poker with Rumsey and others – some of them dead in the towers – on Thursday nights, after his separation from Lianne. This is his connection with the dead, and with what he shared with them, as well as the towers themselves.

Trauma is the persistence of shock, a constellation of memories that haunt and torment, and which bend and buckle the personality of the sufferer into a posture like the twisted remains of a devastated building, a posture that reflects its distortion on to the world as seen from its new odd angle.

As counterpoint to the intensity and persistence of the traumatic memory, Lianne lives with the fear that she will follow her father into the confusion of Alzheimer’s Disease, and does voluntary work with a group of sufferers whom she sees coping with their own departure from memory, even as they struggle with the shock of 9/11.

This is DeLillo’s theme, poignantly and plangently described. It is a hymn for the New York of 9/11, and its fallen. It is quietly and sparely voiced, without theatrics. No theatrics are needed, or possible; the event is epic enough and requires no embellishing. DeLillo pares everything down, giving a short, shorn, direct, unencumbered and economical account of a vast moment that in the very slenderness and terseness of its telling, captures the horrible power of its impact.

The perpetrators are not forgotten. One is followed from Germany to flight training in the US, and then into the fuselage of one of the planes seconds before impact. It is a brilliant stroke to have the reader accompany the terrorist into the tower, the baton of narrative passing directly from that moment to Keith’s being thrown across his office and then struggling in shock through the debris and haze to Rumsey’s office, where the dying man with the smashed head lies slumped in his swivel chair.

The title of Falling Man is taken from a performance artist who, in the weeks after the atrocity, to the rage of many New Yorkers, suspended himself above the streets of the city in the attitude of one who had leapt from the towers to escape the ferocious blazes consuming them. He called himself the Falling Man. Other images and gestures capture the horror of the occasion more graphically; this one captures the piteous vulnerability of the victims as no other can.

This novel is not easy reading for two reasons. One is its potent and disturbing rendition of the events of 9/11 and their effects. The other is that every scene is written so sparely that one has to work to piece together who we are with, what is happening, when and where. It is not friendly reading. But the effort is worth it – and perhaps necessary.

FALLING MAN by Don DeLillo Picador, £16.99; 246pp

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