As a young man I moved to a small Swedish town where no one spoke English, and much of the time I felt as out of place as if I had been on the upper slopes of Mount Everest, where nothing grows and the air is too thin to breathe. But over the years I adapted. I learned to speak the language, and then to think in it, and finally to feel in it and to dialogue with myself in words I can’t translate to English without a conscious effort.

Sweden then was a disciplined place. Violent crime was almost unknown. There was a subculture of unofficial, manly violence, but only directed at other men. One fiercely denunciatory book on Sweden included in its indictment of the country the readiness with which criminals confessed to their crimes once caught. Being cut off from society, the author maintained, was the most terrible fate that could befall a Swede, so they would confess in order to be reconciled with it.

The mysterious shimmer, or out of focus quality, that crime had then was reinforced by the mystification of criminals. Their names were hardly ever published in the newspapers – instead they would be referred to by their age so that the accused would be no more than ‘The thirty-five-year old’, or some other distinguishing characteristic. This rule, hugely frustrating to the impulses of the tabloid press, is largely still observed today in the old media.

Even Christer Pettersson, the man suspected as the murderer of the Swedish Prime Minister Olof Palme, was known in the newspapers for a decade as ‘the bayonet man’, because after a drunken quarrel with another drifter he killed him with a bayonet.

But very occasionally the names of some truly famous criminals would be published. One of them was Clark Olofsson, a bank robber from Trollhättan, a town about 30 km from Lilla Edet, where I lived with my girlfriend. Olofsson was only 16 at the time of his first conviction, but even after his adolescence ended he kept stealing things and thumping people. In 1973 he became famous when a friend took six women hostage in a bank in central Stockholm and held them for six days while demanding Olofsson’s release from prison. As part of the hostage negotiations Olofsson was allowed out of prison by the police to join his friend inside the bank vault, where he shot and wounded a policeman who was spying on them. The hostages were rescued, and Olofsson and his friend were sentenced, but the freed hostages maintained that their captors had been acting to protect them from the police – hence the term ‘Stockholm syndrome’.

This gave a strange glamour to Trollhättan, a town which might otherwise have served as the boring centre of Swedishness, rather the way that Reading is for England. The oldest part of the town is probably the cemetery, which dates back to the Neolithic period. For much of that time, Trollhättan made no impression on history. It was simply a small town by a gigantic set of rapids and waterfalls on the Göta Älv, the great river that empties Lake Vänern. These rapids – and the smaller set at Lilla Edet, downstream – made the river unnavigable, and so cut the interior of Sweden off from access to the North Sea. In the late eighteenth century work began to blast a series of locks around the rapids; by 1900 these had been rebuilt and enlarged twice and it was now possible to navigate all the way to Stockholm by water. Small industries started to grow, and in the early twentieth century the rapids were finally emptied, bypassed by a hydro-electric power station that for many years supplied as much as a quarter of all Sweden’s electricity.

In all this prosperity and usefulness, Trollhättan remained resolutely uninteresting. It was a quiet, respectable town of stolid buildings. The only trace of architectural individuality was the Victorian library in a small park by the canal. When the filmmaker Lukas Moodysson wanted a place to represent the soulless prosperity of 1970s Sweden for his wonderful satire Together, he chose Trollhättan to film in.

Nonetheless, it appeared to me a place of electrifying glamour when I lived in Lilla Edet down the river. Trollhättan was where you could buy drink – at least between nine and five on weekdays, not at all on weekends. And in the library there were record players on which you could listen to music in English. Lilla Edet had neither of these amenities. If you wanted drink there – and my in-laws were of the view that no respectable person would – it had to be ordered twenty-four hours in advance, and delivered by bus. The only licit stimulant was tarry black coffee, drunk from small cups around a sugar lump held between your front teeth.

But in Trollhättan there was rock and roll music. I took the bus in one day with my girlfriend, that first summer before we got married, and we bought four cans of beer. I drank one on a bench in the park in the sun, like an alcoholic, and then in the library asked to play a Lou Reed album through the headphones. When the music started I was startled to feel the hairs all along my forearms and thighs rise up in gooseflesh, and for twenty minutes or so I lived as intensely as I ever did that summer. Then we took the bus home. That was excitement.

The world that we lived in then was boring partly because it was so exceptionally safe. Trygghet, a word normally translated as ‘security’, was what society promised to deliver. You were protected from economic storms – from uncertainty – and held tightly in a mesh of mutual obligation and duty by the state. For instance, if you purchased a bottle of wine, but dropped it before you could get it home, the systembolag would replace it, free, if you returned the smashed top with the cork or cap still in place. Society was compensating you for an accident that was not your fault.

If you lost your job, it was understood that there would always be another. If a family broke up, the state would pay maintenance, although it would also demand it back from delinquent fathers later. It was understood that no one should suffer through no fault of their own. Sickness, of course, was the business of the state. The health service was brusque and unfriendly, but it was always there. Television was a state monopoly, absurdly conformist and astonishingly boring. It was all for our own good.

The origins of this society lay in the convulsive economic and political revolutions of the preceding century. A poor, rural, Christian society had been transformed into a rich and largely urban one, in which science and social democracy had assumed the authority of the church. It was still ordered and hierarchical, but now the root of power was supposed to lie at the bottom, with the workers, and not at the top.

Sweden’s passion for security can’t be understood without imagining the titanic insecurities the upheaval of industrialisation and social democracy caused. Work, schools, housing, and families – all the anchors of everyday life – had been hauled up from their old places and lowered onto strange new grounds. It’s no wonder people clung to an idea of safety, order and discipline.

The northern provinces in the interior of the country were emptied of their workers, who moved down, with their families, to newly built satellite towns around Stockholm, Malmö and Gothenburg, hundreds of miles away. The institutions by which the Swedish state had defined and understood itself – the church, the monarchy and parliament – were all profoundly changed. Except for parliament, all seemed threatened with extinction. The generation coming into adulthood in the middle of the twentieth century went from extreme poverty to being citizens of one of the wealthiest countries in the world. The great Social Democratic Minister for Finance, Gunnar Sträng, who ran the economy from 1955 to 1976, had left school at fourteen to work, and had siblings who died of TB. My mother-in-law grew up in two rooms with thirteen other children, eating the resin exuded by pine trees instead of sweets. She died of Alzheimer’s in a modern, clean nursing home, stripped back to the essentials of her childhood. Asked how things were in the home, she replied that she was content: ‘I eat well here’.

One of the certainties in this tumble into the future was the belief that change was inevitable and must always lead to better times. A strange fusion of Christian belief and Marxist historicism made it seem certain that history flowed in one direction, onward and upward. Modernity meant that Sweden would inevitably become richer and more peaceful, and the rest of the world would follow its lead.

Of course this faith often appeared to the outside world as an opaque and chitinous smugness. The fear that it concealed or made manageable was even harder for foreigners to see than it was for the Swedes themselves. Anyone who felt themselves on the outside of that society, as I did at first, risked being consumed by impotent rage.

For those on the inside, doing the right thing meant both safety and a kind of imprisonment, like swimming within a shark cage. Leave it, and you would be torn into pieces. When my mother-in-law left her husband, she lost, at one blow, all her friends but a Danish couple. No one in town would speak to her. There was nowhere else to live. What was outside the cage was not only dangerous but invisible.

Since those days, almost everything has fallen away. The old securities and certainties have gone into the oblivion reserved for the incomprehensibly recent past. Since the early 1990s, almost all the jobs in Trollhättan have disappeared. Saab, which had been world-famous, was first bought by GM, then turned into an assembly plant for cars designed and largely prefabricated elsewhere, and has finally shut down. In three years, 5,000 jobs vanished and what replaced them had no air of permanence. In Uddevalla, on the coast 30 km away from Trollhättan, the shipyard closed, and its great cranes were brought down with dynamite. The Volvo factory was taken over by Ford. The army base closed. My friend Christer, who had been a welder in the shipyard, now has to travel 200 miles a week for work, long after he thought he’d have a safe pension.

The countryside has also changed. The forests alongside the valley of the Göta Älv seem empty because of their lack of undergrowth. The conifers grew out of thin and rocky soil, covered for the most part in pine needles or interrupted by boulders dropped by the retreating ice sheets. The ground is broken and irregular except for some small pastures near lakes. It was brutal and unforgiving to farm, and the last smallholdings disappeared in the middle of the twentieth century. But as the countryside emptied out and became a resource for leisure, something wholly improbable happened. Wolf packs started to reappear in places where they had not been seen for centuries. They came originally from northern Russia, through Finland, and then down through Swedish and Norwegian Lapland. Any that lingered among the Sami reindeer herds were killed, so the survivors kept moving until they reached the forests of central Sweden, and some even made it down as far as Lilla Edet.

In the early years of this century I made a radio programme about the phenomenon, and in the course of it was taken into the forest a few miles north of Lilla Edet to see the maggot-covered corpse of an elk which had been killed by wolves. My guide was an angry man, a bundle of testosterone beneath a baseball cap, who worked in one of the few small workshops left in the valley. He was probably the man who had shot the wolf responsible and he certainly wanted me to believe he was: to be an expert hunter, and part of a team of expert hunters, was a distinction granted to few.

All his stories about wolves – how they took sheep and dogs as well as elk; how cunning they were, and how difficult to kill – seemed to be a way of expressing an attitude to foreigners, or migrants as they are nowadays known. At the time, they were a subject as hedged about with taboos as drink had been when I arrived in the blazing afternoon of social democracy.

Nonetheless, the formation of an immigrant ghetto in Trollhättan had been well under way by 1980. An area of new housing to the east, Kronogården, cut off from the rest of the city by the main road to the north, was slowly filling with Finns, and, later, Yugoslavs and Chilean refugees from the coup that overthrew Salvador Allende. The rest of the town appeared to continue as if Kronogården did not exist. After the Chileans came the first Middle Eastern refugees – Kurds and Assyrian Christians from the Iran/Iraq wars, then Lebanese fleeing the Israeli incursion. Bosnians, Macedonians and Kosovans followed during the Balkan war. Somalis started to arrive and rapidly established themselves in Kronogården. All these people were fleeing genuine persecution, or at least war and poverty, but there were many more of them than anyone had planned for or foreseen and there were jobs for very few.

The only publicly admissible attitude was straightforward and very widely – though not universally – shared: all immigrants were welcome and would be cared for until they could contribute. Anyone who disagreed with this was regarded as some kind of neo-Nazi. Some of them actually were. Even in the seventies there was a skinhead grouping calling itself ‘Keep Sweden Swedish’ active in Gothenburg. I used to get handed their leaflets along with those of the Maoist and Trotskyist groupuscules in the town centre. Over a period of months in 1991 eleven people were shot, and one killed, by an unknown sniper in Stockholm. All were dark skinned. The gunman turned out to be half-German, and to have been teased as a foreigner in Swedish schools. At around the same time there was a small riot in Trollhättan involving skinheads and immigrants; later, the Shia mosque was burned down.

These episodes were regarded as variously deranged and criminal. It was unthinkable to suppose they had any political aspect, that they might later form part of democratic politics. Then, in the late nineties, a small group of students at Lund University, small town boys from the backwoods, took over a moribund neo-Nazi group, the Sweden Democrats. They were skilled and enthusiastic politicians who used the hostility, the scorn, and the intermittent physical violence that was directed against their movement to weld it together. It was originally based in Skåne, the southernmost province once part of Denmark, which has a long tradition of hostility to the distant authorities in Stockholm, a regional accent and a belief in its own self-sufficiency. It is, in short, Sweden’s answer to Yorkshire, and its economy is not in good shape. The old heavy industries have all disappeared, and the bright ‘knowledge industries’ that replaced them have nothing to offer the old working class. At the same time, because it is the nearest part of Sweden to the European mainland and now joined to Denmark by a bridge, it has a high number of refugees and foreigners.

So the Sweden Democrats, as the party was called, found room to grow in the local politics of Skåne.

The dynamics of integration that played out in Sweden were not essentially different from those in other Western European countries: the metropolitan elites were in favour, the people among whom the immigrants settled were often hostile, and those furthest away from both among the most hostile. But there were two large differences. The first was the solid identification of patriotism and virtue with an openness towards refugees. All of the newspapers, all of the television channels, and all of the major political parties made this identification. The second was the role of Sweden’s neighbours. Both Denmark and Norway had much more restrictive policies and rhetoric. Both had flourishing anti-immigrant parties who formed part of the political system, entering coalition governments and openly negotiating with the other parties. In Sweden, unpleasant and sometimes violent extremism on the left was regarded as a legitimate expression of political opinion – while your reputation as a public intellectual could survive praise of Pol Pot, it could not endure publicly expressed hostility to immigration.

When the Sweden Democrats finally entered parliament in 2010, it was on the back of a commercial which showed an elderly white woman pushing her walking frame across a shadowed hall towards a desk where two benevolent civil servants sat, ready to hand her money. But she is overtaken from behind by a crowd of women in burkas. The camera cuts to two emergency stop handles hanging from the ceiling. One is labelled ‘Pensions’, the other ‘Immigration’. A woman’s voice, husky, urgent, says ‘You can choose between a brake on pensions or a brake on immigration. Vote for the Sweden Democrats’.

This advertisement was rejected as racist by state TV and at least one commercial channel, but was broadcast to an immense audience on YouTube. The Sweden Democrats swept into Parliament with twenty seats, which more than doubled to forty-nine at the next election in 2015. The other parties united around a policy of complete denial. They refused to debate with the SD in public, so far as this was possible; refused to eat with them in the canteens and refused to pass legislation that was dependent on SD support. That might have worked twenty years before, when the only source of national news was the newspapers and the television. But by this time there was a thriving underground of news sites spreading the Sweden Democrats’ message, and the official silence merely amplified their appeal to people rebelling against the culture of conformity around immigration.

The same alternative media worked to loosen the secrecy of crime reporting. The culture of official anonymity and obfuscation, which back in the last century shielded the Swedish from crime, suddenly seemed much more sinister. The shower curtain which once preserved decency now revealed the silhouette of an unknown murderer. Crime, and especially violent crime, had risen enormously since the seventies. The homicide rate nearly tripled, from 122 in 1975 to 338 in 2016; violent assaults have risen over the same period from 21,509 to 88,576. Some of this is the result of redefinitions, whether legal or social, so that behaviour that had once not seemed criminal is now treated as such. Rape is the clearest example, which makes the statistics confusing, but eye-catching: an increase from 769 cases reported in 1975 to 6,715 in 2016.

During this period, immigration from outside Scandinavia rose greatly, too. The link between increased crime and immigration is contested and complicated, but it is universally believed to exist, and the result is that people find anonymised reports of crime in the newspapers more disturbing than they used to, since many of them believe that the names being concealed are no longer plain Swedish ones like Olofsson and Pettersson.

So when I read the news of a multiple murder at a school in Trollhättan in October 2015, the first thing I wanted to know was whether it was an ethnically motivated crime, directed either against immigrants or against white Swedes. Within six hours of the massacre a photograph taken by one of the pupils was published online, showing the murderer posing between two children. He was armed with a sword and dressed like a futuristic storm trooper created by an imagination nourished on George Lucas and Heinrich Himmler. His face was invisible behind a Darth Vader mask and at his belt hung a mobile phone that he had loaded with music from an apocalyptic comedy horror band called ‘White Zombie’.

All three faces had been concealed by pixilation, but the murderer’s stringy white neck was clearly visible. The girl was wearing a flowered Middle Eastern blouse, and in an interview with one of the tabloids, which called her ’Sara’, she mentioned that she had five siblings in the school. So, obviously, not an ethnic Swede. No working class native Swede would have a family that size. It had been a racist attack. Everything else about the killings was still opaque.

Much later, when I read the 450-page police investigation, some of the real names became clear. They were supposed to have been all redacted but the victims had lost their anonymity, and the names of the witnesses had not all been consistently crossed out. I have used changed, but consistent, names in what follows. In the smartphone photo as it appeared in the police investigation, the faces of the two children are blanked out with Post-it notes. The boy to the left, Baha, is making a gesture of confidence with his right hand: thumb and index finger curled together, and the others spread forward. His other hand is invisible, tucked under the elbow of Anton Lundin Pettersson, the killer. On the other side, Sara is posing with a similar self-confident innocence. Pettersson’s arm is round her shoulder and he holds her in an almost proprietorial way. She has a hand in her pocket and leans outwards a little, three quarters on to the camera.

The two children, along with the girl who took the picture, had left the classroom halfway through a maths lesson. Discipline appears to have been largely absent in Kronogården school and pupils were texting rumours to each other in class quite openly. In this particular class a girl had been rung up by her sister and who said, ’Don’t go out because a man has come to school.’ Baha and another couple of boys then rose from their seats and looked out of the door, where they saw a man dressed in black carrying some kind of iron bar, walking down the corridor. Baha left the classroom and joined Sara, who had bunked off from her class with a friend on the excuse of needing to collect a pen.

Sara asked the masked man if they could have a selfie, and though he said nothing, he beckoned her and Baha towards him: her friend took the picture. The three children had been followed out by the teaching assistant, Nazir Amso, who arrived just as Baha realised that the sword was real and sharp, and not just a Halloween prop. ‘It was like something you’d use to cut meat,’ he told the police later. In fact it was sticky with the blood of the two young men whom Pettersson had already killed. Baha shrank away, just as Nazir Amso approached Pettersson and tried to pull his mask off. Pettersson stabbed him in the stomach; the children broke away and ran.

Nazir Amso, bleeding and trying to run, called out to Baha and Sara to call an ambulance. At the foot of the stairs, Sara glimpsed a boy lying on the floor by some potted plants. There was a lot of blood. She ran on.

In the lobby she saw another man – Lavin Eskander – half sitting, lolling to the left. There was more blood on the floor. She ran through the door to the shops across the road.

Baha had run the other way. He came out into the schoolyard and kept on running till he reached the shelter of a little grove of birch trees.

Nazir Amso, still bent over and half running, made his way down the stairs, following the route Sara had taken out the front door. Outside the Arab-run shop across the road he collapsed on a patch of grass and people came to help while waiting for the ambulance. He remembered nothing after that, he told the police who interviewed him in hospital.

He died on December 3rd.

The two bodies at the foot of the stair belonged to Ahmed Hasan, a fourteen-year-old Somali boy, and Lavin Eskander, a teaching assistant who had been helping him with his lessons. They were the first black people Pettersson saw when he arrived at the school.

By the time Sara, Baha and Amso left the building, all of the classroom doors had been shut, and an atmosphere of panic gripped the school. The headmaster, one of the few people to have kept his head, heard of the murders from two of his staff, who had been talking on a landing overlooking the atrium and cafeteria when they saw Pettersson walk in and without speech or hesitation smash his sword down on the head of Lavin Eskander. Confused and afraid, they rushed into the headmaster’s office to tell him what was happening.

Pettersson hacked Ahmed Hasan’s arm and pursued him up the stairs. From the landing at the top of the stairs, a Swedish cleaner saw ‘a Somali boy’ running towards her – she didn’t notice that he was hurt. She looked down and saw a man collapsed on a table in the cafeteria area at the foot of the stairs. She thought he might have fallen into a diabetic coma. As she moved towards him, another man came up the stairs: she noticed the helmet first, then the Darth Vader mask. He swerved past her. She turned back to look at him, and at that moment saw him stick a sword into the stomach of the boy. She wondered if it was a joke for a moment; then she started running towards the cafeteria kitchen, where she locked the door behind her and rang the police. They were by now getting calls from all over the school, and the four people on duty in Trollhättan station were in their cars and on their way.

The first two police officers at the scene, Hans Detlev and Katarina Lindblom, reached the school within ten minutes of the first murder and ran in the front door with guns drawn, heading across the atrium and up the stairs. Halfway up they caught sight of Pettersson walking away from them. They shouted ‘Police! Stop’ and he turned.

The shots were so nearly simultaneous that neither heard the other’s gun, and as Pettersson clutched his stomach and dropped to the floor both thought that they had been the one to shoot him. The official report does not clarify who did.

Either way, Petterson was not dead, only mortally wounded. He was lying on his back, without the sword or helmet, but with a large knife stuck in his belt, close to his right hand. Only as she knelt beside the now handcuffed and dying Pettersson could Lindblom see the man she’d shot. He had a new haircut, his pale cheeks were dusted with glitter and his eyes had been ringed with black.

I have read the police investigation four or five times, taking careful notes, puzzling out names and following the timeline of Pettersson’s actions. There were more than just human witnesses. The building itself kept records: the doors logged when they were opened; closed-circuit TV watched over the public areas. Everyone who had seen Pettersson – and many who hadn’t – were interviewed later that day. The story built through this overlapping accumulation of detail until I knew exactly where he walked and who and what he struck with his sword. There is a photograph of the receipt for the sword, and of the box in which the helmet came. But there is, by contrast, an extraordinary blankness about Pettersson’s inner life and motives. The surface of his life was smooth as melamine.

When I came to Trollhättan three months later, no one would talk to me about what had happened, no one would help me see beneath the surface. The fact of the killings stood alone. I had the police report. I sat in the deserted cafeteria, at the table where (I later realised) Ahmed Hasan had been sitting when he was attacked. I walked for a while in the cemetery, trying not so much to think as to sense myself into an understanding of the story. It’s almost like parkland, with a small lake in the middle. There are few trees except along a small ridge above the lake with a menhir, about waist high, at its summit.

Close to the lake the older tombs had weighty old Swedish names carved in black into pale granite, often with crosses and quotes from the bible. Further out, the Swedish graves grew less demonstratively Christian. Then I came to a region of Middle Eastern names; some had Christian symbolism but Arabic inscriptions; Orthodox Christians with Slavic names and then the Bosnian Muslims, still with their inscriptions in Roman script. In the Muslim section all the graves were turned in the same direction, towards Mecca where the sky would never be this grey and cold.

Right at the edge of the burial ground the grave of Ahmed Hasan had been kept fresh and raw: a scalloped, irregular mound of earth, patterned by rain, with no grave marker but a little sign asking that no flowers or markings be laid by it. Next to it was the grave of Nazir Amso, buried under a vast heap of white and yellow flowers, stuffed animals, and messages to the dead man.

Beyond the Muslim graves, the cemetery field stretches on towards distant houses. There was room for as many people again as lay buried from all the preceding centuries. Who would fill those spaces? There was a future there, waiting to be written in. I thought that almost all the Swedes I had spoken to were frightened of what would come. Their refusal to talk to me was not just the product of a natural distaste for journalists, and a wish not to be made into entertainment or instruction for strangers to whom the town owed nothing. There was also, I think, a fear of something nameless that would be summoned if it was ever named. In a graveyard, perhaps, such thoughts come easily.

The only people who did speak openly about their fear of the future were the Sweden Democrats, but their fear was uncontrollable and apocalyptic. I had rung up their office in Uddevalla to talk about the murder, and the party secretary was more than happy to discuss it.

‘Before 2012 it was taboo to be in SD,’ he said. ‘If you had a job, you had to be quiet about it. Then I retired, and now I couldn’t give a damn what anyone thinks. We’ve destroyed our welfare system. We had such good schools once – world-class schools, and skilful engineers, people like that. Of course society has to change, but back then we had a solid base to change from. And now we don’t have money for anything. They’re eating us out of house and home. All our resources go to the immigrants, and they never actually start work. After fifteen years, only a third of them are in full-time work . . .’ He went on. I did not try to stop or correct him. The collapse of discipline, convention and coherence in society and especially in schools, the collapse of the Swedish manufacturing industry, and then the arrival of refugees all seemed to him part of the same huge process that only the Sweden Democrats could stand against. The murder did not seem to him to have any connection with his own party. It was part of the general process of degeneration and moral disintegration which was destroying his country.

His feelings could not be admitted in the respectable Swedish press. In the web archive of the local paper, I came across the story of a Dr Novak, who had been expelled from the local branch of the Conservative party for racism. She was herself an immigrant, originally from Czechoslovakia, and had spent a lot of her life doing charity work helping immigrants. But in an email to a friend who was working with Somali refugees, written while she herself was working as a volunteer in a Kenyan refugee camp, she quoted the English author Richard Dowden – a man who fell in love with Africa in his late teens and has spent much of his journalistic career covering it with courage, charity and thoughtfulness – in order to help her friend understand aspects of Somali culture. ‘Somalis have built a warrior culture: quote “If I cannot wash the face of the land with my enemy’s blood, I am not a Somali” . . . Only when all the ammunition has run out can we try to reach an agreement . . . Their self-esteem is inborn. Self-sufficiency and arrogance are taken by them as compliments.’ Dr Novak finished the email by writing: ‘We can expect lots of problems in Trollhättan with the number of Somalis who have arrived. Not exactly easy to integrate.’

The recipient shared this email with her colleagues, and was threatened with disciplinary action as a result. Meanwhile, Dr Novak was forced into retirement and then drummed out of the local party. Merely thinking that Somali culture was not compatible with Swedish values was condemned, and anyone who expressed it publicly had to be driven from public life.

This seems to me the reaction of a deeply frightened and anxious society. That’s hardly surprising. The anxiety over integration is also in part an anxiety over how Swedes should be Swedish. Almost everything that made a good citizen in 1950 had been rejected by the late sixties, only to be replaced by new orthodoxies almost as rigid. Where formality had been compulsory it was now forbidden; national pride had been replaced by pride at being the most internationalist country in the world; science, not duty, was the guide to conduct.

But there was no time to get used to these new rules. Their complete hegemony lasted only about thirty years, before the collapse of social democracy showed that its apparently solid underpinnings had melted into thin air. In the years after 1990, solidarity was replaced as an ideal by competition; modesty and egalitarianism by a worship of celebrity that also fed off envy, but used it to fuel an entirely different attitude. A slightly absurd provincial pride was replaced by an equally uncritical and rather more humourless fixation on Stockholm.

The older Sweden Democrats I talked to were strangers in their own country, almost as alienated as I had been that first long summer in Lilla Edet. Sometimes they seem to me even more exiled from the country of their birth and of their upbringing than are the refugees and immigrants they so resent. In the age of cheap flights and ubiquitous internet, emigrating from one country or one culture to another is not nearly so much of a dislocation as it once was. The Swedish authorities experimented for a long time with models of bilingual multiculturalism, where children were encouraged to nourish the heritage of their parents’ culture. That was controversial but it has, in any case, been overtaken by the ubiquity of the internet. The old home countries, and the families left behind there, can now be reached at any time, through a device that everyone carries in their pockets. The Swedish past, though, is a country which is harder to reach.

None of this much helps to explain Anton Lundin Pettersson. He was born in 1994, long after the ideals of the sixties had disappeared. His whole life had been lived under the new rules, in which he seems to have been as much at home as anyone.

He had no known political affiliations; nor did his parents. He had few friends, none of them close. One remembered that he used to play a lot of Skyrim: ‘A game where you kill dragons with a sword’. His disappearance from his social scene left no ripples. He had no regular girlfriend and no regular job. He had had a variety of internships of the sort arranged to alleviate or conceal youth unemployment all across Sweden today, and the last of these employers told him that he would not be getting permanent work a fortnight before the murders. That appears to have been the trigger for him to buy the sword and helmet, but it is impossible to know when he decided to use them. He left no clues to his inner life.

On the morning of the murders he left a neat, sparsely furnished bedroom in the flat his parents owned in town. The bed was tidily made up, with a red and white striped duvet. On a tidy computer desk lay a copy of an English picture book: Signs, Symbols & Omens: an Illustrated Guide to Magical and Spiritual Symbolism.

Beyond the wish to kill anyone whose skin was not white, he doesn’t seem to have indulged in any of the attempts at system building that distinguished the much more deadly Norwegian racist killer, Anders Behring Breivik, who killed 77 people with guns and explosives in 2011. Of course, had Pettersson had Breivik’s equipment, he too could have killed dozens in that school: the children were all trapped in classrooms behind flimsy glass and wooden doors.

Pettersson’s outfit was vaguely Nazi, but I think the inspiration for it came more from Star Wars than Mein Kampf, although the ‘storm troopers’ in Star Wars were modeled on the Nazis, as were their helmets. He seems to have had no theology of evil in the way the some nihilists do. He just killed.

There are two kinds of reactions of horror to the police report on his crime. The first comes from the precise and visceral details of the injuries inflicted and the deaths they caused. The other is the question that echoes at the edge of hearing, which has to do with the opaque banality of his life: the sense that beneath all the social explanations, and even all the psychological ones, there is just a blank. This anomie is hardly new. I remember the (white) teenagers who used to stand around the entrance to what was then the only shopping mall in Gothenburg in 1977. They looked at once completely lost and completely at home. As blankly as a CCTV camera, they watched the respectable people who passed before their eyes. ‘There is no accusation in their shallow eyes’, I wrote after seeing them one day, without any idea of what I could do with the sentence.

Pettersson, though, would not have been noticed anywhere. His absolute ordinariness suggests something, too, of the sense of unfairness which Trollhättan feels as a result of his crimes. He could have been anyone, anywhere in small-town Sweden. And – the echo moves into consciousness – anyone in small-town Sweden might be him.