A teenager in green and black paramilitary gear is speaking Russian in a hushed, low voice. An overgrown graveyard is barely visible off to the right of him. Traditional Ukrainian cloths hang on a few crosses. A white stork passes overhead. "This should be the cemetery," he says. He puts away his GPS. He holds his hand-held Geiger counter up over a mound of dirt that covers radioactive machinery; the beeping goes wild and the numbers shoot up. 1.1.7, 1.1.8, 1.1.9. "This is beyond the scale," he says, half-scared and half-thrilled. He moves away from the spot. The carcass of Chernobyl's Reactor No. 4 punctuates the distance.

On 26 April, 1986, the Chernobyl Nuclear Plant's Reactor No. 4 exploded, and the ensuing nuclear fire burned for 10 days, releasing 400 times as much radiation as the bomb dropped on Hiroshima. A radioactive rain blanketed parts of Ukraine, western Russia and Belarus. Twenty-eight years later, Chernobyl remains the world's worst nuclear accident.

The long-term effects and death toll of Chernobyl are controversial and hard to quantify. The World Health Organisation expects a total of 4,000 deaths linked to the event, including those who died in the initial disaster, and cancer cases that have developed and will develop afterwards. Other organisations, such as Greenpeace, contend that the health hazards have been wildly underestimated and that eventually, the death toll will hit nearly 100,000.

Grim reminder: One of Chernobyl's reactors (Chris Bairstow/The Babushkas of Chernobyl)

The fallout was political as well. The Soviet Union's inability to deny or control the story arguably represented the first cracks in the superpower's totalitarian myth – cracks that would widen into glasnost and within just a few years shatter the Soviet state.

As the first generation of Ukrainians born after the Chernobyl tragedy comes of age, a small subculture of them is now doing the unthinkable: defying government prohibitions and illegally entering the highly radioactive Chernobyl Exclusion Zone, or "Dead Zone"– for fun. This group is monitored and pursued by the police and is not fond of journalists. Members revel in the forbidden, recover meaning from Soviet detritus, and take digital appropriation to new extremes. "It's a post-apocalyptic romance," as one young man put it.

Shortly after the accident, the Soviets declared a 1,000-square-mile zone uninhabitable, and mass evacuations began to take place. Nearly three decades later, the zone remains among the most contaminated places on Earth, and at its centre is the ongoing hazard of the concrete entombed Reactor No. 4, with 200 tons of lava-like nuclear material underneath.

In pictures: Chernobyl's forgotten victims Show all 25 1 /25 In pictures: Chernobyl's forgotten victims In pictures: Chernobyl's forgotten victims Chernobyl's forgotten victims An elderly lady wanders into the Exclusion Zone at an informal crossing point between officially contaminated and officially ‘clean’ space. Radiation is not stopped by the fence, and nor are people. Alexey Furman In pictures: Chernobyl's forgotten victims Chernobyl's forgotten victims A young girl plays on her grandparent’s small farm near the edge of the nuclear Exclusion Zone. Growing your own food is an important survival strategy for people who live near Chernobyl, despite the risk of contamination. Thom Davies In pictures: Chernobyl's forgotten victims Chernobyl's forgotten victims In a village near the Exclusion Zone, a woman holds a photograph of her husband who worked as a liquidator after the 1986 Chernobyl accident. He died soon after the disaster, and she attributes this to exposure to harmful levels of radiation. With no support from the State, she says that the government have “cheated us all the time”. Thom Davies In pictures: Chernobyl's forgotten victims Chernobyl's forgotten victims An elderly widow holds a photograph of her husband who worked as a liquidator after Chernobyl and died from exposure to harmful radiation. Alexey Furman In pictures: Chernobyl's forgotten victims Chernobyl's forgotten victims An elderly woman stands in her house in a village that borders the Exclusion Zone in north-central Ukraine. A photograph of deposed former President Victor Yanukovich and opposition politician Klitschko are stuck to the wall. Alexey Furman In pictures: Chernobyl's forgotten victims Chernobyl's forgotten victims A Soviet War memorial near the Chernobyl Exclusion Zone. This landscape has witnessed a lot of suffering with heavy fighting during WW2, as well as acts of atrocity against the Jewish population. The invisible danger of radiation is a less tangible threat, with one war veteran comparing the two traumatic experiences: “At least when the Nazis were in my village you could see them”. Alexey Furman In pictures: Chernobyl's forgotten victims Chernobyl's forgotten victims A man holds the blue and yellow flag of Ukraine at a memorial to the Chernobyl catastrophe in downtown Kiev. This weekend marks the 28th anniversary of the world’s worst nuclear accident. As my friend Arthur Bondar said yesterday “Ukrainians and Russians once saved the world from radiation together. Lets save the world now from a new war and commemorate all the victims of Chernobyl” Alexey Furman In pictures: Chernobyl's forgotten victims Chernobyl's forgotten victims A man walks past a memorial in Chernobyl Thom Davies In pictures: Chernobyl's forgotten victims Chernobyl's forgotten victims A man and his dog stare through the barbed wire fence into the forbidden space of the Exclusion Zone. Many people subsidize their income by illegally entering the Zone to collect scrap metal, which they can then sell. Local border police patrol the fence and occasionally arrest trespassers or demand the payment of bribes. Thom Davies In pictures: Chernobyl's forgotten victims Chernobyl's forgotten victims It is common for people to wander through the forbidden forest of the Exclusion Zone to gather wild food such as berries and mushrooms, or to hunt for wild game. Food is both eaten their families and sold informally. Untouched by human activity – apart from invisible radiation - the Exclusion Zone has become a haven for wildlife. Thom Davies In pictures: Chernobyl's forgotten victims Chernobyl's forgotten victims The infamous damaged nuclear reactor at Chernobyl. In 1986 a combination of human error and bad reactor design caused a nuclear meltdown that would impact so many people’s lives. A new gigantic sarcophagus is currently being constructed to cover the old reactor and stop further radiation leaks. Thom Davies In pictures: Chernobyl's forgotten victims Chernobyl's forgotten victims Aleksander worked for years as a liquidator and driver inside the nuclear Exclusion Zone. He shared many stories about life on the edge of the Zone, and how he would never leave the landscape he grew up in. He once told me “the USSR is something that is now invisible, it is just a concept, where as Chernobyl is everything that you can touch, that you can see, that you can feel”. Aleksander died last year. Thom Davies In pictures: Chernobyl's forgotten victims Chernobyl's forgotten victims A man in Stari Sakoli village stands in his field. In the background the Exclusion Zone can be seen beyond the trees. Alexey Furman In pictures: Chernobyl's forgotten victims Chernobyl's forgotten victims Alcohol for sale in a shop near the Exclusion Zone. Alcoholism is a big problem in this region, as it is elsewhere in Ukraine. With one in four people in Ukraine struggling below the poverty line and an uncertain future - many men turn to drink. Some here believe it protects them from radiation. Alexey Furman In pictures: Chernobyl's forgotten victims Chernobyl's forgotten victims A woman in Krasilivka village cuts grass using a traditional scythe, near the Chernobyl Zone. Alexey Furman In pictures: Chernobyl's forgotten victims Chernobyl's forgotten victims An elderly lady who lives near Chernobyl cries while remembering events that followed the disaster. Many people have personal stories of loss and tragedy relating to Chernobyl. Alexey Furman In pictures: Chernobyl's forgotten victims Chernobyl's forgotten victims Two mothers and their children wait at a bus stop just west of the Exclusion Zone. There are very few jobs or investment in the region, and little compensation for having to live on contaminated land. With nearly one in four people in Ukraine below the poverty line, and the IMF demanding benefit cuts, life for people near Chernobyl is getting harder. Thom Davies In pictures: Chernobyl's forgotten victims Chernobyl's forgotten victims A babushka stands on her small plot of land in a village near Chernobyl. Immediately after the accident the authorities advised people not to eat a variety of homegrown produce, but the Ukrainian State only gives a tiny amount of compensation each month ‘to buy clean food’. Despite the threat of pollution, people here remain very attached to their land. Alexey Furman In pictures: Chernobyl's forgotten victims Chernobyl's forgotten victims Kids kill time in Orane village, five kilometers from the Exclusion Zone. There are few jobs or prospects for young people in this marginalized region. Alexey Furman In pictures: Chernobyl's forgotten victims Chernobyl's forgotten victims Chernobyl campaigner Sergey Petrovych Krasilnikov holds a photograph of the damaged nuclear reactor in his flat in Kiev. He attributes his disability to radiation from the accident, having been in a wheelchair since the early 1990s. Many people feel abandoned by the state, and do not get paid the compensation that they are owed by Ukrainian law. Alexey Furman In pictures: Chernobyl's forgotten victims Chernobyl's forgotten victims Children in a school in Orane village, 5km from the Chernobyl Exclusion Zone. Each year some children are taken abroad for a month by charities for ‘Chernobyl Children’ based in Spain. As a result, most kids in Orane speak some Spanish. Alexey Furman In pictures: Chernobyl's forgotten victims Chernobyl's forgotten victims Five residents of a village near the Exclusion Zone in Ukraine watch the world go by. All of them attribute Chernobyl radiation to a wide range of illnesses from cancer to diabetes, as well as personal stories of loss and bereavement. The number of fatalities from the nuclear disaster is highly debated. Alexey Furman In pictures: Chernobyl's forgotten victims Chernobyl's forgotten victims A liquidator holds her medal awarded to her after she helped clean up the highly polluted landscape around Chernobyl after the accident. Despite having the correct documents, many liquidators still fail to receive the compensation that is owed to them. Thom Davies In pictures: Chernobyl's forgotten victims Chernobyl's forgotten victims A boy who lives in a village that borders the Exclusion Zone plays in a river that runs through the contaminated territory of Chernobyl. Thom Davies In pictures: Chernobyl's forgotten victims Chernobyl's forgotten victims A baby is christened in the only functioning Church in the Chernobyl Exclusion Zone. After the ceremony the priest said “There is no radiation here” Alexey Furman

Just three kilometres from the reactor is the plant's company town, Pripyat. Today, the radioactive ghost town's abandoned apartment buildings slowly fall apart and pay quiet homage to the nearly 50,000 people who fled. Pripyat is full of still-lifes; a table set for dinner, a big wheel squeaking in an elegiac, fruitless wait for children. Wild boar snuffle through rusted playgrounds, and kindergarten napping areas are scattered with wide-eyed, broken dolls, thick with radioactive dust. From the top of a high-rise, one can see "the sarcophagus", three kilometres in the distance, covering Reactor No. 4, which sits cracked and rusted and wafting radioactive dust. Twelve-foot-long catfish swim in its long-defunct cooling pond.

For the "post-apocalyptic romantics" who have taken to sneaking into the zone, a visit to Pripyat has become the Holy Grail. They come here for reasons they can't fully explain.

V surreptitiously makes his way past rusted, still bumper cars, it is dangerous to move through Pripyat at dusk. Usually he goes only at night. He keeps his dosimeter [a device for measuring radiation] off so as not to make noise and alert police who might be on patrol. V walks into a nine-storey building, up the rickety stairs and into an apartment with peeling wallpaper and many shades of grey. "Dobryj den." Good afternoon, he says to three young men who are already there. They had agreed in an online forum that this is where they'd meet. This is their hideout.

The term that has come to be used for those who sneak into the zone is "stalkers." It's a word with deep resonance in this part of the world, first appearing in a 1971 science-fiction novel called Roadside Picnic, by the Russian brothers Arkady and Boris Strugatsky. In the novel, there are "post-Visitation" (presumably by aliens) worlds in which "zones" harbour inexplicable, deadly phenomena. The government tries to tightly regulate the area to keep a group of thieves called stalkers from sneaking in and taking out artefacts. Stalkers must evade both the police and a strange array of invisible, deadly booby traps.

Overgrown: An abandoned village house (Anonymous/The Babushkas of Chernobyl)

Eight years after the release of the book, Russian filmmaker Andrei Tarkovsky adapted it into the film Stalker. Both book and film became cult classics in the waning years of the Soviet empire. Roadside Picnic and Stalker, created 15 and seven years, respectively, before the Chernobyl accident spread radiation throughout the region, proved prescient: an apocalyptic event leaves behind an invisible force with the power to create mutants. It's not entirely fiction now, unfortunately.

They arrive at Rudnya-Veresnya after walking for several kilometres in the woods. It is a village inside the zone that was evacuated, but not buried, as many others were. A cottage is overgrown with rambling, bare vines and a shed next to it has totally collapsed. They enter, measure the levels at the fireplace, and shuffle through decades of old debris; memories of a life – postcards from a beach holiday, a notebook with a list on it – left in the wake of a hasty departure. They flip through old newspapers and find Communist Party ID cards. "It's a time capsule," says one visitor. "If you want to see how it was in the USSR 30 years ago, you can go to the Chernobyl Zone."

In 2007, the stalker legend was updated when a team of young Ukrainian designers released a video game that they called S.T.A.L.K.E.R. (Scavengers, Trespassers, Adventurers, Loners, Killers, Explorers, Robbers), set in the Exclusion Zone around Chernobyl. It has sold more than five million copies. It also spawned a subset of fans who were not content to confine their gameplay to the screen. Loosely organised squads of gamers began to experiment with breaking into the zone.

Since the zone was created in 1986, there have been isolated looters. But, today, breaking in has become a geek subculture, and for some, an obsession.

Mushrooms are the most radioactive form of life (Anonymous/The Babushkas of Chernobyl)

The nuclear accident, referred to in the region simply as "The Tragedy", may be hazy history for today's twenty- and thirtysomethings, but it remains an open wound for their parents and grandparents. The scores of first responders to the accident were exposed to fatal doses of radiation and were Chernobyl's initial victims. After them, robots tried to put out the fire, but the extreme radiation levels made the machines malfunction. Next, the Soviets brought in soldiers, who became known as "liquidators". Thousands of these young men were presented with a grim choice: two years serving in the bloody Afghan war, or two minutes shovelling radioactive debris off the top of Chernobyl's reactor. Most of them took a shot of vodka and opted for the latter. (Vodka was, and still is, widely believed by Ukrainians to combat radiation.) Most of the liquidators are now sick or dead.

One 14-year-old stalker told me, in hushed tones, how his grandfather was one of the Chernobyl plant's control-room engineers. The Soviets put his grandfather and his colleagues in prison after the accident (Soviet officials blamed plant workers for the disaster). "He got out a few years later and died of cancer. I never knew him," he says.

Most stalkers hide their activities from their families; others do it in defiance of them. One casually explained his status as a card-carrying "Child of Chernobyl" due to his exposure at a young age. "It allowed some privileges. We were sent to retreats and summer camps to rest and improve our health. My grandfather fought the fire in the zone for a month," he continued. "He would not be happy if he knew I was going. He was there against his will. I go because I want to. It would be unimaginable to him."

The stalker generation has grown up with a distrust of government and authority, first forged under Soviet rule and furthered in a post-Soviet era beset by corruption and economic turmoil. Another oft-cited piece of cultural fallout from Chernobyl is a pervasive fatalism; a widespread victim mindset, which creates a feeling of "lacking control over their future," as Fred Mettler wrote in the report Chernobyl's Legacy. "A number of adolescents and young adults who have been exposed to modest or small amounts of radiation feel that they are somehow fatally flawed and there is no downside to using illicit drugs or having unprotected sex," he adds.

A radiation warning sign (Anonymous/The Babushkas of Chernobyl)

Sex, drugs, and radiation: stalking might be seen as the adolescent acting-out of a generation that feels it's got nothing to lose. But for many stalkers, it's clearly something more.Online communities have emerged to trade information, tips and advice on what routes are safe from the police, which entrances have become too dangerous, or where supplies are hidden. Experienced stalkers sometimes mentor younger wannabes. Pseudonyms are always used. In-person meetings are only cautiously pursued, as stalkers worry about police sting operations.

Some forums are open only to those who've achieved a certain level of success. Stalkers pursue a set of thresholds – or "acceptances" – by reaching an increasingly challenging (and dangerous) set of destinations. "Dogs and security are the biggest problem in the Chernobyl zone, not radiation, not zombies," says one veteran who almost lost an eye while fleeing police.

Of course, radiation seems like the most obvious danger, though the health risks aren't as clear as you might think. Nearly 30 years after an accident, nuclear contaminants with short half-lives are no longer a threat, and acute radiation poisoning would only take place if you "went into the sarcophagus and sat on the fuel containing rods", says former Chernobyl official Vita Polyakova. But there are still elevated background radiation levels in places such as Pripyat as well as super "hot spots" of severe contamination, many of them undocumented. The risk of ingesting radionuclides – the radioactive strontium and cesium present in dust, water and food grown in the area – is the most acute threat.

"Maybe on the outside we got more radiation than usual," a stalker concedes, "but once we leave, radionuclides are washed off our skin and that's it. The greatest risk is when it gets inside your body. That's why we try to bring everything with us – water, food."

"But D ate apples in the zone," I remind him.

"I did, twice. They were so big!" D chimes in. "I drink water in the zone, eat apples, and everything is good for me. No second head," he adds with a small smile.

A cross inside the radiation zone (Anonymous/The Babushkas of Chernobyl)

Among the stalkers I meet, their concerns for the risks – and attentiveness to radiation protocol – vary. Some use dosimeters, others don't or don't trust them "There's no guarantee the dosimeter will show a hot spot," says one stalker, correctly. Some reference radiation maps. Some take care to bring their own water supply; others drink from the highly contaminated ponds or rivers inside the zone, sometimes out of necessity: "We got lost and ran out of water. We had to collect morning dew from the greenery until we could find water."

Others drink water in a misguided show of videotaped heroics. One infamous stalker, seemingly maligned by other stalkers and officials alike, is a Russian named Sergey Papov. Alexander Naumov, a retired military police officer who now monitors the zone, showed me a video of Papov drinking from the Pripyat River near the plant's cooling pond, which is surely the most contaminated water in the zone. "By doing this, he is sending a message that there is nothing dangerous about the zone," says Naumov with disgust.

It is V's fifth night in the zone, the second in a Pripyat apartment strewn with cheap high heels from the Seventies and decaying ceiling tiles. He has explored the kindergarten, tinkled piano keys in a music shop, and picked his way through a destroyed gym, read dusty handwritten love letters from another era, crossed rivers, and pilfered condensed milk. He has found the peace that the zone delivers him.

"In S.T.A.L.K.E.R.," Alexey Sytianov, one of the game's creators, says, "the most important thing is the mystical atmosphere. Being around abandoned, destroyed places while heading towards one big goal and true wish, the player starts to be in contact with something – something that is even hard to describe with words. It comes from the destroyed surroundings, and from what he is believing in."

What do the stalkers believe in? An invisible enemy that might kill them at 50 years old rather than 70? No. Walking through their past on their own terms? Maybe. Responding to the energy and potential of their youth, despite the risk? It seems so. Clearly, stalking delivers them the present moment – the lawless wild greenery and pathless reality of the zone – that makes them, if only for a short while, masters of their destinies.