One of the biggest drug raids in China's history took six years to plan and 14 hours to execute.

The target? The village of Boshe, a drug haven known by local people as “The Fortress”.

Before the raid, they thought Boshe was impenetrable.

Everyone there shares the same last name, Cai, and some say up to half of the village was involved in making chemical drugs.

There's no doubt they made themselves rich. Inside Boshe's Chinese temples, the drug makers used to burn sacks of real money to give thanks to their ancestors.

It was one of the first places in communist China to see flashy sports cars.

For years, waves of police from the province where Boshe lies, Guangdong, kept trying to raid the village. And for years, they failed.

Every time they tried to enter Boshe and shut down its clandestine laboratories, the villagers anticipated their arrival.

Scores of people, including young children and the elderly, would join arms to block the village's entrances. Sometimes, they would use motorcycles to surround the police, threatening them with AK47 rifles and grenades.

If officers managed to break through, they would discover the drug labs had disappeared.

The Fortress lived up to its name.

Boshe’s drug makers had eyes and ears in the local Communist Party and the regional police.

So, to overcome the gangs, the top levels of China’s government spent years quietly inserting Beijing loyalists into village life.

One by one, local officials suspected of leaking information to the traffickers were removed and replaced with those thought to be clean.

Finally, Chinese elite paramilitary police had to come in to do the job. They couldn't trust the local forces.

Three thousand of them descended on the village at 4am one dark morning in December 2013.

They dropped from helicopters and marched in on foot. Some arrived on speedboats at the nearest port 8km away.

They jammed phone signals so no-one in Boshe would be alerted they were coming.

Then, waves of police scoured the warren of narrow cobblestone streets inside the ancient village, which dates back to the 13th Century.

Immediately, the village's Communist Party secretary was handcuffed. Cai Dongjia was the area's most senior official.

Chinese state media reports trumpeted him as the “godfather of the village”, a kingpin who protected all the drug makers.

Next on the hit list - the drug barons who lived in mansions next to Boshe's dirt roads.

Clambering over the elaborate security gates, the police forced open locked doors, shining flashlights into the faces of the mansion's bewildered occupants.

In the basements of the massive houses, and dilapidated buildings nearby, they found what they had come for - almost three tonnes of methamphetamine and, a staggering 400 tonnes of meth ingredients.

Many houses contained stacks of cash and piles of gold bars. Many houses were well armed with guns, which are illegal in mainland China.

The raid even uncovered a makeshift explosives factory.

The authorities knew they would find large quantities of crystal meth in the village - the crystalline form of methamphetamine. After all, crystal meth is China's top chemical drug.

The area surrounding Boshe is thought to be responsible for one third of China's meth production.

But police then uncovered something they weren't expecting - more than half a tonne of a different drug, ketamine.

It was known that ketamine was a rising problem in China, but few had any idea that it was made in Boshe.

Many know ketamine as a horse tranquilliser, though it's not just used on horses. It's a trusted veterinary drug because it can be used across the whole spectrum of animal species.

Originally developed for field hospitals in the Vietnam War, ketamine is still used in developing countries as an emergency anaesthetic.

It has the advantage of knocking recipients out, without the need for advanced equipment to administer it or to monitor breathing.

But this old drug is getting a new life in night clubs. Recreational users say ketamine lifts them out of their bodies, into other worlds. Many feel like they can fly or float. They can escape reality.

For decades, it was only manufactured by pharmaceutical companies. Technically, it was too complicated to be made by amateur chemists.

But in the past five years, that has changed.

Chinese drug gangs have cracked the code, figuring out how to manufacture large batches of cheap ketamine.

It's a “worrying development” says Martin Raithelhuber, a synthetic drug expert with the UN's Office on Drugs and Crime. From his office in Vienna, it's Martin's job to monitor global drug trends.

Drug traffickers don't bother to steal ketamine from legal sources anymore. “We're talking about something bigger than that,” he says.

Instead, they're making their own. It's largely a Chinese breakthrough.

“Other countries in the region report clandestine laboratories but not to the extent China has,” Martin says.

China's underground ketamine laboratories can't be compared to ramshackle homemade operations featured in parts of US TV series Breaking Bad.

“Under those conditions, you cannot produce ketamine,” Martin says, his normally calm voice rising an octave.

It's likely that Chinese gangs had help setting up their ketamine operations, probably from gangs in Mexico.

Others might have helped too. Increasing numbers of transnational groups from South-east Asia, Colombia, Iran, Pakistan and West Africa are also co-operating with groups inside China, making the production and export of drugs like ketamine an international effort.

I wanted to interview the Guangdong police, but after months of negotiations, they refused my request.

They are proud of the successful raid on Boshe, but they explained over the phone they didn't feel their work in the area was complete.

They warned they were preparing more raids.

A world away from Boshe, a city in the UK knows the draw of ketamine all too well.

It's so popular in Bristol that it's earned its own nickname - Bristol Crystal.

British tourists returning from India used to pack bottles of veterinary ketamine in their luggage, disguising it as rosewater.

That's when Jim Bartlett first heard of ketamine. He's been working as a drug counsellor at the Bristol Drugs Project, a community agency that helps those suffering from an unhealthy dependence on drugs or alcohol.

Jim's worked in the field for 20 years and over time, he's developed a special interest in ketamine and the people who take it.

“Ketamine becomes a huge part of people's identities,” he says. Entire networks of friends take it together.

Jim first encountered the drug in London, where he grew up. In the 1980s, older hippies were using it, he says.

But then ketamine was embraced by a new crowd. Large numbers of much younger people started taking it at “free parties”, impromptu raves held in public spaces.

While some party drugs cause users to be chatty and affectionate, ketamine is a dissociative drug. In small amounts, it might appear that a user is drunk on alcohol. In large quantities, users resemble zombies, off in another world.

“When I got to Bristol in the late 90s, I was very surprised to see that people there were using ketamine,” Jim says.

“They were very confused and stumbling around at parties. And to me, at the time, it seemed quite shocking.”

We meet in a small park in the centre of Bristol, beside a church. Next to manicured flower beds and office workers unwrapping their lunchtime sandwiches, he launches into his story - a 13-year odyssey with ketamine that ended in agony.

“I got to the point where I was doing it because it was the only real thing that anaesthetised the pain that I was in,” Travis says.

“I got into a bit of a spiral where you're just looping around and around. The whole image of a snake eating itself comes to mind,” he says.

Travis doesn't want to share his whole name, though he concedes that many people in Bristol know him anyway.

He's so good-natured that it's easy to make him laugh.

But he also has quite serious, watery blue eyes. They betray the fact that even though he's still quite young, he's led a turbulent life.

Travis started injecting liquid ketamine when he was 16.

“It's weird, because it doesn't seem like it would be a very social thing,” he says, “but compared to things like heroin and crack, where it's very sneaky and people want to go off on their own and do it, people come together in social gatherings when they're doing ketamine.

For six years, Travis injected ketamine. When Indian supplies of the drug dried up, he and many other users in the UK switched to a harsher crystallised version of the drug.

Over pots on kitchen stoves, they would rehydrate the drug themselves.

Travis and many others in the UK believe the crystallised ketamine they were taking was coming from China.

“Different levels of people I was talking to said that it was being mass produced and sent over here,” Travis says.

Travis started getting searing pain every time he needed to use the toilet, twinned with a constant urge to urinate. He also developed stomach cramps that would incapacitate him for hours at a time.

“I always knew it was the ketamine but I just didn't think about it. I knew right from the start that that was the problem but you keep doing it. I was chasing a dream really, because when you first start doing it, the ketamine was really different to what it became.”

Travis was suffering for eight years. When visiting the corner shop 100m from home, he would have to cycle.

If he tried to walk, he would need to use the bathroom before getting home again. The pain would cause him to double over.

As Travis was experiencing the damage caused by ketamine, doctors and drug counsellors were also connecting the dots.

In Chinese karaoke clubs, as in many around the world, there's no general bar area for drinking. Instead, the entire place is made up of private rooms.

Each room has the same basic elements - a couch, a large TV showing song lyrics and some microphones.

Privacy is a key element of the whole experience. When the door closes on a room, the people inside can do almost anything they want.

In many bars, it's common to find alcohol, prostitutes and drugs. And especially in southern China, ketamine is a karaoke favourite.

Using hidden cameras, we shot footage inside a private room in a seedy karaoke bar in the city of Shenzhen.

A group of young men sat in a row all dressed in tight T-shirts, their hair spiked with gel. Most held a mobile phone in one hand and a burning cigarette in the other.

Within minutes, some pull out small plastic bags filled with white crystallised powder - ketamine.

Using credit cards and plastic straws, they cut the drug into short lines on the glass coffee table in front of them.

Over and over, they cut and inhale. They've clearly done this many times before.

On the street in Shenzhen, it only takes a few minutes to find someone willing to speak about ketamine.

“When we started taking it, we thought it was a lot of fun,” says a sex-worker wearing a tight blue dress and scuffed stilettos. She's beaming, but below, she has bruises on her shins.

“I used to take it with the people I live with,” she continues, still smiling.

Ketamine's reach extends far beyond the fringes of Chinese society. China's state media regularly feature stories of unlikely ketamine users.

In March, 16 middle-aged “aunties” were caught snorting ketamine at a karaoke bar in China's southern Zhejiang province.

Members of the so-called “lonely wives club” started attending ketamine parties to relieve their boredom from housework and looking after their grandchildren.

Known as “K powder” or simply, the “new drug”, ketamine can be ordered online and delivered to an address in a matter of hours.

And its low cost means that it is particularly attractive to very young users.

Living in urban labyrinths, and with money in their pockets, many young people are doing things their parents never dreamed of - they're shopping online and communicating almost exclusively with mobile phones.

And increasingly, they're dabbling in recreational drugs. The cheaper, the better, many say.

In Guangdong, a bag of ketamine costs approximately 100 RMB, or $16 (£10) - enough to last a whole night with several friends.

Ketamine is so cheap that it's the first drug that most teenagers will try, in the false belief that it's safe.

In one case which made headlines in China, a teenager in the country's southern Jiangxi province posted photos online of her friends appearing to snort ketamine in a karaoke bar.

“We have been high overnight,” read the caption. “Can't get a taxi back now.”

The photos went viral. Shortly after, the police responded by arresting two of the girls in the photos, a 17-year-old and an 18-year-old.

The woman in the blue dress stops smiling for a brief moment.

“Some people ran into problems taking ketamine. We know it can be addictive,” she says, her voice dropping ever so slightly. “Some even died.”

But then, the moment is over. She flashes her smile again and adjusts the hem of her dress.

The dangers of ketamine are not a subject for open discussion.

The doors at the Baiyun drug rehabilitation clinic are always locked, betraying the fact that the patients inside aren't always there by choice.

One of China's largest private drug rehabilitation centres is located on a dusty street in the southern city of Guangzhou.

Most of the patients are brought here by their distraught families. Most of the patients are not allowed to leave until they're clean.

Long dimly lit corridors are punctuated by tiny windows.

Every window is covered in steel bars. The patients' rooms are sparse, furnished with only a small bed, a row of hooks, and a television sitting on a desk.

Very little is done to make this place feel like home.

That seems fine with the patients I spoke to, who don't want to stay very long.

One patient, his hair spiked into a fashionable mohawk, is a good example.

He's asked to be called Xiao Zhang, or Little Zhang, though that's not his real name. He's 25 years old, but looks much younger, because of his pudgy, smiley face.

Others shy away from talking about their troubles, but Xiao Zhang is different. He's eager to explain every twist and turn of his story.

“I first started taking ketamine because of a girl. I was secretly in love with her, but I was fat and she rejected me. I was heartbroken,” he says, shaking his head.

“She was my first love. But your first love often hurts you the most.”

At the time, Xiao Zhang was studying computer programming at a local college.

“My friend told me about this thing that could help me forget everything. I said 'No', but he said I wouldn't understand until I took it. I couldn't resist the temptation,” he says.

“By the time I was 23, I started selling ketamine as well as using it. I even recruited younger boys to sell the drug for me on the streets. That helped me earn money so I didn't need to rely on my parents.”

Nurses whisper behind Xiao Zhang's back that he is lazy.

He rarely gets out of bed on time in the morning and constantly misses his morning therapy sessions.

But Xiao Zhang has a different story when he reflects on his time in the clinic so far.

“I've changed so much in the past few weeks,” he says.

“I never used to get up at 7am and go to sleep at 9pm. I never used to eat breakfast before.”

The clinic has 110 drug inpatients at a time.

Every year for the past five years, more and more of them are young people wrestling with a ketamine habit. The clinic's youngest patient is 12 years old.

Wearing a dazzling white doctor's coat, the clinic's head physician, Dr Yang Yong, seems to light up the clinic's shadowy hallway. He walks briskly while discussing the drug that's taking over this place.

“The biggest problem with ketamine is that we still don't understand how big a problem it is,” he says.

“We don't know how widespread it is and how deeply it has infiltrated people's daily lives. Its user base keeps expanding.”

Yang has been working in this field for 12 years and he is seeing an increasing number of young patients.

“Five or 10 years ago, heroin was the mainstream drug but in the last five years, meth and ketamine have taken over most of the drug market,” he says.

“They're looking for excitement and they're easily influenced by their friends. They have little resistance,” he says, frowning.

The clinic's peppy promotional video boasts that Baiyun has “cured” more than 10,000 patients.

Yang explains that up to a third of ketamine patients manage to stay away from the drug, even after two years.

That's a high success rate compared to other drugs, he says with satisfaction.

The Baiyun centre is quick to show off its wide range of treatments, from acupuncture and massage to regular psychotherapy sessions.

Inside the “brain functioning treatment room”, patients recline in padded chairs, their heads encased in a warm plastic box, which plays soothing wave-like noises.

The procedure is supposed to relax brain waves, hopeful looking nurses explain.

The only patient in the room is playing on his mobile phone while the box attempts to comfort him. It doesn't appear to be working - one of his legs constantly jiggles up and down.

For all of its odd treatments, the Baiyun clinic is a world away from China's state-run drug treatment centres.

In China, more than a quarter of a million people a year are sent to mandatory rehabilitation centres.

Inside, inmates wear baggy, striped uniforms and men are forced to shave their heads.

Photos and videos show prisoners marching in long lines, their hands on the shoulders of the prisoner directly in front of them.

One source, who has served time in a treatment centre says he spent most of his time sitting cross-legged in rows on the floor, watching endless videos detailing the dangers of drugs.

As in Bristol, the Baiyun clinic also reports serious problems in the ways ketamine affects the bladder, kidneys and intestines.

The neurological effects of ketamine are still being explored. Most of the users at the clinic admit they cannot process their thoughts clearly any more after using the drug for so long.

At 25, Xiao Zhang has the forgetfulness typically seen in much older people. He often pauses in the middle of sentences, trying to remember the words he wants to use.

It clearly embarrasses and frustrates him.

“Now, I'm slow to say what I want. I used to speak faster and use more logic,” he says, staring at the floor.

A study of 25 repeated ketamine users in Hong Kong in 2013 found damage to several parts of the brain.

Technically, drug counsellors in Bristol and Guangdong say, ketamine isn't physically addictive.

An addictive drug will cause physical withdrawal symptoms when a user suddenly stops taking it - among well-known narcotics, heroin and crystal meth have that characteristic.

However, ketamine produces a strong compulsion in users to continue taking more.

Researchers have yet to agree on how easy it is to develop a dependence on ketamine. “Cravings seem to be a key problem in frequent users,” notes a drug report from the UN in 2012.

But more specific findings have been difficult to pin down. Even though ketamine is a decades-old drug, its new life as an illicit substance manufactured in underground laboratories is a fairly new development.

This makes things more complicated for researchers, who don't know if users are taking pure ketamine, or a drug that is mixed with other chemicals.

At the drug rehabilitation clinic karaoke music is a constant. The clinic has set up a mini karaoke room.

With heavy velvet curtains covering the windows and a plasticky sofa, it's a tame version of the clubs where so many of the patients first encountered ketamine.

A young man sways to the music, dramatically clutching his microphone.

“One word from you and I was intoxicated,” he croons. “I never expected this. I'm holding back my tears.”

Here, music is meant as a diversion. The door on the karaoke room is usually closed, as patients belt out songs, usually ballads recounting heartache and despair.

One patient, at least, is in a good mood.

Xiao Zhang meets me in a hallway near the karaoke room. He's feeling upbeat.

He's only completed two weeks of this program. He's supposed to stay for six more weeks, but already he's planning an early exit. He's anxious to get out in the world again. A job's waiting for him at his uncle's restaurant in Beijing.

“When I leave, I want to start again, both for myself and my parents,” he says as we walk down the clinic's hallways.

“I need to change my environment, I need a new place to live. I need to stay away from my old friends, even break the connection completely.”

That connection might be difficult to break. If Xiao Zhang left this clinic right now, how long would it take him to find some ketamine, if he wanted it?

“One minute,” he says, without hesitation. “Just one minute. One phone call. 'Where are you? Wait for me… and then you get it.'”

Nonetheless, Xiao Zhang's optimism shines through.

“Even if I make one small step, that is still progress. Life is long. I can take my time. I am still young,” he says.

He stops at the end of the long hallway and looks outside, hooking his fingers around the metal bars covering the window. He's smiling.

If you listen to the Chinese media, Boshe has returned to a state of sterile wholesomeness following the big raid.

Gushing newspaper reports mention lush lychee trees and sparkling fish ponds.

A strict new village chief presides over the area and a robust team of 40 police conduct daily patrols.

A visit to Boshe reveals another version of the story.

Foreign reporters aren't welcome in Boshe, by locals or edgy police.

Fifteen minutes outside the village, we switch into a local vehicle, a tuk-tuk - a motorcycle attached to a canvas covered cart.

By pulling a curtain across the back, we're hidden from view. I pull a hood over my blonde hair and crouch down, peeking through the gap left by the curtain.

Entering Boshe, piles of rubbish are everywhere, lining the narrow streets. Emaciated dogs trot through the filth, looking for scraps.

Rising above the filth sits Boshe's millionaire row, a series of mansions bought with drug money. Many are decorated with gold detailing on the sides.

All are guarded by high gates and security cameras. But they are empty now. These were the prime targets of the raids.

We stop for a moment in the village square.

This village dates to the 1200s and more than 40 temples dot its streets.

It's possible to see how the centre could be beautiful if it was cleaned up.

But this is no place for tourists. Everywhere we go, we attract unfriendly stares.

In the square, locals approach as soon as they spot a camera. People crane their necks to peer into the tuk-tuk as we drive past.

Perhaps that's not a surprise. Recently, 13 more locals received the death penalty for trafficking.

We drive to the outskirts of Boshe. As we approach a distant field, farmer Cai Jingsong leaps into view.

A tiny leathery man, he barely waits for us to leave the tuk-tuk before launching into his story.

Cai's family has been working the same fields outisde Boshe for at least three generations. He's seen the village change from a tiny farming community into a world-famous drug den.

But that's all ancient history in Cai's mind. Right now, he's desperate to talk about his cattle. His dead cattle, in particular.

“I used to have eight cattle, but now I only have five because three died. They ate something poisonous,” he tells me. “Now, the only way I can make money is to sell cattle manure as fertiliser.”

As he speaks, he gestures wildly. He's talking so loudly that he appears to be straining his vocal cords.

He points off into the distance to explain where his land sits - one patch there, another even further away. He used to grow peanuts and sweet potatoes, but that's not an option anymore.

“When they started making drugs, I was working away from Boshe,” he says. “When I came back, my land was polluted.”

Many farmers around Boshe cannot grow crops because the chemical run off from the drug production has tainted their land. Drug labs also used up most of the area's fresh water, leaving the fields around the village dry and cracked.

The river next to Cai's field is choked with dark, sludgy water. A nearby pond is littered with empty chemical bottles.

So, why didn't Cai get involved in the drug business? Is that an option?

“I'm too afraid!” he bursts out.

“The others say that nine out of 10 people in the drug industry end up dead. Others tried to persuade me to go into the drug business before. I wished them good fortune, but I just don't have the guts.

“The drug business here is shrinking,” he continues. “But the gangs are still very powerful.”

“In Boshe village, the drug dealers are up here,” Cai exclaims, reaching his hand above his head.

“My family is way down below. There's nothing we can say against them.”

He invites us home. As soon we enter his traditional courtyard house, it's obvious why he refuses to leave Boshe.

With its peaked roofs and an open courtyard decorated with swirling motifs, it's a Chinese farmhouse straight out of a Hollywood movie set.

Cai's grandfather built the house - his portrait hangs prominently on the wall. His elderly mother, sitting silently in the corner, grew up here too.

But there's no time for a guided tour. As soon as we arrive, Cai bolts into the kitchen to tend to an enormous pot sitting on the stove. Inside is a bubbling mixture peppered with strange grasses and herbs - a soup the farmer makes for his cows.

He insists it protects them from the poisoned land.

But Cai can do little to protect himself. Over tea, he tells me that if drug production continues here, his land will become more contaminated and he'll shut down his farm.

That's when he'll finally give up on Boshe.

Many others are already long gone. When leaving the village, a police checkpoint is papered with dozens of mug shots of Boshe's most-wanted.

Rows and rows of stern faces, all staring straight ahead. Red ink has been stamped over the ones who have been captured.

Most are still on the run.

Then, I meet someone familiar with the fugitives.
It took months to arrange, but one insider agreed to explain the inner workings of Boshe's drug operations.

He insisted he wasn't involved in making drugs. However, his relatives, including his ex-wife, his current fiance and her family, were all arrested in that big raid on Boshe.

The meeting came with two conditions. First, I had to agree to hide his face and his name. And second, we had to meet in an eerie, abandoned warehouse in the mountains outside Shenzhen.

Together, we look at photos of Boshe's fugitives.

The man points out the people he recognises, some of the drug bosses and others involved in production and trafficking, but it's clear that he doesn't like this exercise.

He keeps looking over his shoulder, even though we're in an empty room.

He is quite young, in his mid-20s. And even though he insists he's not a drug maker, he looks like he could be training to become one.

A tight white shirt stretches over his sizeable belly and he's chain smoking eye-wateringly strong cigarettes. Eventually, he begins to open up.

“After the drug making technique came in,” he continues, “the first family really worked together on it and the drug profits were really high. One family taught another how to do it.”

For years, the village thrived by producing mountains of meth. The relative's own clan specialises in meth, and he's quick to advertise its wonderful properties, explaining brightly that if you take it “you can play cards for days”.

A rival clan specialises in ketamine, he says.

“Drug making is based on market demand,” he says, conceding that “the demand for ketamine is almost the same as the demand for meth.”

But Boshe's success became a weakness. The chemical labs grew over time, becoming too elaborate to move quickly.

“In the past, when the labs were smaller, it just took one hour to move them,” the relative says.

“But, the more drugs that were made, the bigger they got. It was all too much. So the labs couldn't be moved in an hour anymore.”

“The raid was a big surprise,” he says.

“All the telephones stopped working in the village because the signals had been jammed.

“People nearby tried to warn people in Boshe, but the calls couldn't get through. When the villagers found out, some tried throwing the drugs into the sea.

But ultimately, the raid did little to dent drug operations in and around Boshe.

Lighting yet another cigarette, the man exhales a cloud of smoke before explaining that the region doesn't just make the final versions of the drugs.

Crucially, they also manufacture the precursor chemicals that go into those drugs. Boshe's gangs have mastered entire supply chains.

And that makes drugs even cheaper. Ketamine now costs less than meth, he says.

“Drug prices are still dropping because lots of drugs like meth are becoming easier and easier to make. There are too many people who know how to make drugs, so the prices are really cheap.”

China's leaders are reacting to the problem, launching high-profile crackdowns.

A six-month drug operation that started late last year resulted in 133,000 arrests, and more than 600,000 people were caught taking drugs.

The numbers are almost double those for the same period a year earlier - a dubious victory for police.

It was a violent period, too - nine police were killed and another 657 officers were wounded.

Globally, ketamine seizures are soaring, rising 85% between 2012 and 2013. Much of the world's ketamine is streaming out of China.

Until 2012, 60% of the world's ketamine seizures took place on the narrow border between mainland China and Hong Kong. Experts believe that number is probably even higher now.

With so many police watching Boshe, operations are more secretive now, the insider says. But they haven't stopped.

“In China, more than one place is producing drugs,” he continues, pulling the last cigarette from the pack.

“Boshe is just one of the places with large-scale drug production. In lots of Chinese provinces, there are a lot of places producing this kind of stuff.”

On a sunny afternoon in Bristol, Jim Bartlett, the drug counsellor, leans back on a park bench and laughs.

“Bristol Crystal” is only slang for ketamine because it rhymes, he argues.

But the mood darkens when Jim learns that the street price for ketamine is dropping in China.

After a few years of turbulence, Bristol and other UK cities are undergoing a ketamine “drug drought”, an extreme shortage of the drug.

“I can't help but thinking there will be another wave,” Jim groans.

“People will become more interested once the price drops.”

The street price of ketamine seems to strongly influence how many want to take it.

Before, it was sometimes called “the poor man's cocaine”, but not anymore - its cost has soared by nearly 400% in the past few years in Bristol.

A change in the law is one probable reason.

In 2014, ketamine was upgraded from a Class C to a Class B drug in the UK.

Possession of ketamine could lead to a five-year prison sentence. Supplying it to anyone can result in a 14-year sentence.

“It's happened a few times over the years that we've been aware of a drug drought,” says Jasmine, a young woman who works as a counsellor alongside Jim at the Bristol Drug Project.

“Ketamine just seemed to disappear and the really small quantities that were left just seemed more expensive.”

“Before that, ketamine had a reputation for not having many side effects. People were selling it and people were making quite a lot of money from selling it,” Jasmine says.

“But after the change in law, I think it made people realise that it was quite a risky thing to be doing.”