On​ 12 December 1884, Henry James took a break from writing the novel that would be published as The Princess Casamassima and went on a research trip to Millbank Prison on the north bank of the Thames. The prison was swampy, labyrinthine and dark. In the novel, Hyacinth Robinson, an impressionable young bookbinder, goes there to visit his dying mother, whose criminal past, we soon learn, has a central role in her son’s mentality and is a cause of his undoing, as he becomes lost in a London filled with social venom and anarchist plots. Unusually for James, there was a good amount of research involved in the preparation of the book, a lot of pavement-pounding and Naturalist-style spectatorship, and he was determined to marry the particularity of London’s new political instabilities to a story of one family’s tragic tussle with ambition and the secrets of a changing city. ‘The country is gloomy, anxious,’ he wrote in a letter to Grace Norton early in 1885, ‘and London reflects its gloom. Westminster Hall and the Tower were half blown up two days ago by Irish Dynamiters.’

Today, the site of the old prison is marked by a bollard that once stood at the head of a flight of steps leading to the river. If you look across the water you can see the headquarters of MI6. A hundred yards upstream from the bollard is a curved, modern apartment block called Riverwalk. On 29 November 2019, a young man called Zac Brettler went out onto a fifth-floor balcony at 2.23 a.m., looked down into the dark water and jumped. The event was captured on a CCTV camera set up on the MI6 building. Zac died, and the question of who the young man was and why he jumped, as well as the mystery of what was happening in the flat behind him, would become central to a story that remains both legible and oddly unfathomable. By asking the right questions, Patrick Radden Keefe establishes a series of links that not only open up this heartbreaking case but sound a klaxon on the cosplay of a whole generation.

Zac Brettler was in many ways a typical 21st-century boy. He wanted everything but was fearful that he might never get it, so he invented himself. That’s not an exclusively London thing, but it is rife in the city. His elder brother, Joe, went to University College School (UCS), but Zac failed to get in, so ended up at Mill Hill School. ‘Education mattered a great deal to the Brettlers,’ Keefe writes, ‘as it did in their wider social milieu, in which families were often quietly judged by other families over where their children went to school. Zac was old enough, and socially perceptive enough, to grasp this, and it must have stung.’ The ‘top schools’ of Britain are stuffed with the beneficiaries of economic selection and intellectual streaming. To be at Mill Hill, Zac seems to have felt, was to be rejected in social terms, banished from UCS, Westminster or Highgate (to say nothing of Eton or Harrow), which might have been survivable but for the existence of the internet, a disinformation superhighway leading all too quickly from personal disappointment to fantasy.

The independent schools of London are weirdly inefficient when it comes to refusing the well-heeled scions of the Russian mafia. Mill Hill was apparently full of them, swanking around in designer togs, and Zac was massively impressed by them. One day he hired a chauffeur to take him home from school. At seventeen, he was always suggesting that his parents buy a better car. ‘He was into the whole money aspect of life in general,’ his schoolfriend Dimitris said. Zac decided he might feel altogether happier if he were a pupil at Harrow. He was rejected. ‘Harrow “did not think that he was quite good enough”,’ Keefe reports, ‘adding that the competition was fierce and “coming from all over the world”.’ A private shrink he visited at the suggestion of his parents (he didn’t trust the NHS) said he was ‘focused on being very wealthy’, displayed ‘a strong asocial narcissistic flavour’ and ‘a potentially dangerous lack of insight and skewed norms of behaviour’. In no time at all, Zac had launched a fully pretend life and begun to hang out with mysterious people who appeared to big him up.

Akbar Shamji was a rich businessman in his forties who lived in Mayfair. His son attended St Paul’s, another extremely desirable school for the competitive middle classes, and his daughter went to Ashbourne College, where Zac spent his last year as a pupil. Weaned on Instagram, Zac knew a lot about places he’d never visited and people he’d never met. He seemed to be intimately familiar with all the fancy restaurants in Mayfair. His new friend Shamji soon took him to Annabel’s, a nightclub in Berkeley Square frequented by oligarchs and their wannabes. Sporting a Moncler gilet and at one point commandeering a Maserati for a friend to drive, Zac talked of big deals and investments, presenting himself at meetings as a ‘credible’ businessman. Shamji introduced him to someone named Verinder Sharma, a ‘rubber tycoon’. At one point, Zac showed his father, Matthew, a bank statement on his iPad: the balance was £850,000. Zac said it had come from some oil and gas investments, property deals and profits from a car importing scheme he was running with Shamji. It wasn’t clear whether this was real or not. His parents grew more worried about him. A few months after he showed his father the bank statement, he texted his mum to say he’d just used her credit card to pay a small fee for an app.

From this point, as Keefe reports, Zac Brettler dives unknowingly into a world of trouble. Strangely enough, the dangers seem more like fantasies of danger than real ones, like pitfalls in a gamers’ universe – this is the way things always seem in domains where reality is uncertain. His London was a weird place of false identities, fake money, empty properties and dodgy accounts. It slowly became obvious that he had been posing as someone he was not. You might just about get away with this at your average private school, but it becomes hazardous when you’re dealing with the kind of men who are in the habit of enforcing their own fantasies. At some point, Zac lost control of whatever story he had wished to tell about himself, and Keefe’s book traces those pathways out of normality into terror, revealing as much about the way we live now as about the trajectory of this poor boy. We recognise the halls of mirrors that fringe the Thames, the crazily rich Russians having a field day turning the capital into a huge laundromat for the washing of dirty money, and just as familiar is the generation of young people, privileged yet stranded, trying to work out who to be in this miasma of glitz.

Zac was last seen driving around London with Shamji in the latter’s Mercedes. When questioned by his parents, the businessman told them Zac had been using a different surname, Ismailov, and claiming to be the son and heir of a Russian oligarch. He told his friend Andrei that his dad was an arms dealer. He claimed to be close to the Russian model Daria Radionova. He said he lived in style at One Hyde Park, ‘a superluxury development’. He claimed to have a personal chef. He showed off his tattoos (they were fake) and told people he was a heroin addict. He claimed his father was dead, his mother lived in Dubai and he had inherited a fortune. The book reminds us of something we should never forget: liars really enjoy other liars, until they don’t. Verinder Sharma wasn’t a rubber tycoon but a hustler, bouncer and drug dealer. He was, Keefe writes, an expert at ‘finding ways to insinuate himself into the lives of people who had money, cultivating a queasy friendship, before turning on them, ferociously, with demands’. After the drive around Mayfair on the evening of 28 November 2019, Shamji and Zac went to Sharma’s apartment at Riverwalk. Shamji left at 1.25 a.m., returning to the building an hour or so later, just as Zac jumped. He went up to the apartment for twenty minutes, then went outside to the walkway beside the Thames, where he was caught by the camera peering over the river wall into the water. Afterwards, the men claimed that the boy had stayed the night, and it wasn’t until the next morning that they discovered he had disappeared. Text messages show that Shamji and Sharma thought Zac had a fortune of at least £205 million, and believed they were entitled to half of that sum. In fact, he had £4 in his account.

The MI6 camera seems to prove that Zac was alone on the balcony. No one pushed him. Keefe and Zac’s parents think he was trying to jump into the river to get away from his so-called friends, rather than to kill himself. He nearly made it, but his hip clipped the embankment wall. A year later, Sharma died of an overdose in the apartment and the Met, saying ‘they couldn’t prove any crime had been committed in the first place,’ gave up on what had been a particularly inept investigation.

London Falling is a book about a city, but it’s also a book about families and shows that even good parents can lose sight of their children. I was often reminded of Oliver Twist, another book about London and parenting, in which exploiters and fantasists turn out to be waiting in the shadows. But neither Dickens nor James was faced with the omnipresent truth-denial that characterises our era. I wonder, if only for a moment, whether those of us who write fiction are playing into the hands of the era’s escapist bias. In this period of lies, a well-sourced piece of non-fiction can sometimes feel like a way of drawing us back from the self-propounding multiplicity of possible realities.

As a form, literary non-fiction has a powerful tradition, yet it has tended to feel the need to define itself against the virtues of good fiction. John Hersey, for example, tied himself in fancy knots trying to describe his journalistic masterpiece, Hiroshima. ‘Things we remember for longer periods,’ he wrote, ‘are emotions and impressions and illusions and images and characters: the elements of fiction.’ Hersey wasn’t keen on other people’s efforts to define his genre. He deemed Truman Capote’s phrase ‘the non-fiction novel’ to be ‘appallingly harmful’, and when considering the writing of Tom Wolfe castigated ‘the would-be journalist who cannot resist the itch to improve on the material he digs up’. These writers, he argued, shared a fundamental defect: ‘the notion that mere facts don’t matter’. He admired Norman Mailer, but had no time for his arguments on behalf of ‘the True-Life Novel’. What offended Hersey was not so much the naming of forms but that question of trust:

In fiction, the writer’s voice matters; in reporting, the writer’s authority matters. We read fiction to fortify our psyches, and in the pleasure that that fortification may give us, temperament holds sway. We read journalism … to try to learn about the external world in which our psyches have to struggle along, and the quality we most need in our informant is some measure of trustworthiness. The Executioner’s Song [Mailer’s Pulitzer Prize-winning book about the murderer Gary Gilmore] may satisfy us as fiction – it does me – precisely because the author’s voice is so pungent, so acute, so eloquent, so very alive. But there is deep trouble when we come to the journalistic pretensions of this novel.

Keefe’s work is so alive that one may say, in the way of the New Journalists, that his reporting has the texture of fiction. But actually it’s the worlds he writes about that have the texture of fiction – built of lies, secrets, silences, denials, dissolving identities – and his factual precision makes him a social realist in the era of fabulation. In these postmodern times, where everything and nothing might be claimed for truth, Keefe’s writing draws on the same fundamental idea of the journalist as Hersey’s, not as juddering style-machine but as trusted witness who seeks above all to prove and to show what is verifiably true.

A person employed today to handle the press – Karoline Leavitt, let’s say, at the White House – can be almost messianic in their defence of lies, ridiculing journalists who ask ‘inappropriate’ questions in pursuit of the truth. In the smaller world of London’s criminal underworld and its spheres of influence, the case of a young man such as Zac Brettler can become lost among the competing denials, but this reckless habit of reality-smearing now seems to be truly international. Keefe quotes the BuzzFeed reporter Heidi Blake: citizens in Putin’s Russia, she writes, ‘became acculturated to a certain “dissonance” in day-to-day life. They could no longer trust that a suicide or an overdose or a heart attack or a fall was really what it appeared to be … This erosion of accountability and erasure of the clean line separating fact from conspiracy created a “fog of ambiguity”.’ And this, as London Falling beautifully invokes, is the pea-souper of today, a place where victims fall and bad people vanish.