Inside a row of rusting cages, 15 adult moon bears are imprisoned in varying degrees of apathy and distress.
Some lie on their backs in the tiny enclosures, unable even to stretch out; other loll their heads or chew listlessly at the bars of the cage in tortured, repetitive motions.
Every few days, the bears will be sedated, a needle will be inserted into their gall bladders and bile extracted to be sold as a cure for anything from haemorrhoids to a hangover.
More than 20,000 bears are kept, most in appalling conditions, across eastern Asia to satisfy an age-old obsession with the medicinal and magical power of products culled from exotic animals.
Yet there is a ray of hope for some of these bears, as public awareness of animal protection and welfare gradually rises across Asia.
Last year, Vietnam's government promised to close down all its bear farms by 2022, following on from a promise by the country's traditional Chinese medicine community to stop prescribing bear-bile products by 2020.
That means bear farming is very clearly coming to an end in Vietnam, "once and for all," said Jill Robinson, founder of Animals Asia. "I think they realised that both internally and internationally, bear-bile farming was becoming a very unpalatable subject."
There has been progress as well in South Korea, where the Government completed a sterilisation programme on captive bears last year as part of an effort to phase out farming.
Outside these bright spots, however, the picture is much grimmer. China is the centre of the industry and of demand for bear bile products. Bear farming remains legal in China, and here at least 10,000 bears are still kept in cages on nearly 70 farms.
Asian black bears - closely related to the American black bear - live in mountains and forests from Japan to China and across the Himalayas to India. They are known as moon bears because of a white marking on their chests, roughly in the shape of a crescent moon.
The first known record of the use of bear bile for its medicinal properties comes from a Tang Dynasty document that dates to AD 659. But the idea of farming living bears to extract bile originated in North Korea in the early 1980s before rapidly spreading to China, Vietnam and Laos.
Studies show that the acid contained in bile does have medical benefits in dissolving gallstones or treating some liver disease, as well as some anti-inflammatory and antimicrobial properties. But in recent years, it has also been used as an (ineffective) cancer cure or as a general tonic - a draft of rice wine mixed with bear bile, or steeped in a bear's paw, might stave off a hangover, some say.
In Vietnam, though, the industry is on the retreat.
The Government banned the poaching of wild animals in 1992 but allowed bear farming to continue - even though the industry was being almost exclusively supplied from wild populations.
In the years that followed, rising public pressure had an effect. In 2005, shocked by how widespread bear farming had become, Vietnam outlawed the extraction of bile while allowing farms to keep existing animals so they weren't just slaughtered. The number of bears has fallen from a peak of more than 4500 to just over 1000 today, experts say.
The village of Phung Thuong outside Hanoi is where the industry grew up in Vietnam, and is the biggest holdout today: In an area of just a few square km, and among a population of 15,000 people, there are about 195 bears in metal cages, many in small compounds straddling the main road.
Everyone knows that these farms still extract bile, says Tuan Bendixsen, Vietnam country head of Animals Asia. "It's obvious," he said.
Otherwise, why would farmers keep the bears alive?
Bear farmers have the biggest houses and the fanciest cars in the village.
Indeed, as the Washington Post visited one roadside farm, a tray of small brown bottles used to contain and sell bear bile was on the floor in plain view - until a Vietnamese forestry ranger, who is supposed to police the farms, sheepishly picked it up and carried it into a back room, away from prying eyes.
North of Hanoi, it is a different story at a bear sanctuary run by Animals Asia in Tam Dao National Park. Bears rescued from farms arrive here with immense psychological and physical problems, some too weak to walk or climb after lifetimes in cages. Others have lost limbs from the metal traps used to capture them; some are blind because of stress-induced hypertension.
Many have to be gradually coaxed out of confined spaces to get used to their new freedoms.
Today, 175 recovering bears swim in pools, climb ladders and platforms, play gently with each other or stretch out in the shade. Three times a day, workers place vegetables all across their enclosures for the bears to forage and find in an important part of their mental stimulation.
But campaigners are struggling to replicate their Vietnam success in China.
There, bile extracted from bears, in processes involving considerable pain, infection and disease, is baked into powder and sold in a range of products - including eye gel and toothpaste - freely available in pharmacies.
Polls show that public opinion in China overwhelmingly deems bear bile extraction to be cruel and supports a ban on bear farming. But while China has moved to outlaw the trade in ivory, for example, international efforts to convince it to end bear-bile farming may have boomeranged.
"From the beginning, this issue became politically sensitive in China," said Toby Zhang, who has campaigned to end bear farming for more than a decade. "It became about foreigners coming to China to blame Chinese people for doing something."
It is an example of the tightrope that animal welfare groups have to walk as they try to effect change in China without stepping on some very sensitive toes. A 2006 declaration by the European Parliament, calling on the Chinese Government to end bear bile farming, for example, merely served to provoke an angry defence of the industry from the State Forestry Administration.
"The Chinese Government has a bad habit: When they understand something is wrong, they will change - unless it's pointed out by foreigners," Zhang said.
Those sensitivities were exploited by the industry to discredit the campaign to end bear farming, unfairly portraying it as acting in the interests of multinational drug companies out to seize market share from Chinese rivals.
The industry was also boosted when President Xi Jinping threw his weight behind the domestic and global expansion of traditional Chinese medicine, calling it a "treasure of the Chinese nation."
When it came to ivory, the Chinese Government realized that elephant-poaching efforts to satisfy Chinese demand were damaging its image in Africa, a continent where it is keen to increase its influence. On bears, it has dug in its heels.
In 2013, Chinese wildlife groups generated enough public pressure to force Fujian Guizhentang Pharmaceutical to abandon an IPO to raise funds to expand the bear-farming industry. Since then, though, the Chinese media has been warned away from the subject, experts say.
Scientists at Shenyang University in northeast China created a synthetic alternative to bear bile more than two decades ago, but failed to get approval from the China Food and Drug Administration.
The Development Research Centre of the State Council, a government think-tank, issued a report in 2016 calling for the industry to be gradually closed down by 2035. Faced with an internal backlash, that report was soon deleted from the organisation's website.
In March, a member of China's National People's Congress, the country's largely rubber-stamp parliament, introduced a proposal calling for bear farming to be phased out by 2035.
Shi Minghai, president of the Buddhist Association of Hebei Province, said that China should take a lead from Vietnam and South Korea to end an industry that is damaging the country's international image.
The proposal, not the first of its kind, has yet to gain much traction.
In Vietnam, the bear-bile industry was partly a victim of its own success - as production rose, the price dropped. And as the price dropped, people began to consider bear bile less valuable.
"When I first took bear bile, it wasn't from a farm," said 48-year-old Hoang Thi Nga, seeking herbal medicine for her bad back at a mobile clinic run by Animals Asia in Phung Thuong. "Bile from bears kept in a cage is not as effective as bile from bears in the wild."
In China, though, a multimillion-dollar bear-farming industry is continuing to thrive, and has so far outmanoeuvred its critics.