The hum of sewing machines never stops in parts of Guangzhou, a bustling port on the Pearl River in southern China.
It echoes through the factory's open windows from morning until deep dark, as workers finish T-shirts, shorts, pants and swimsuits that will be sent to fill wardrobes in more than 150 countries.
That's the sound of Panyu, the neighborhood known as "Shane Village," a maze of factories that power the world's largest fashion retail chain.
"If there are 31 days in a month, I will work 31 days," one worker tells the BBC.
Most people say they only have one day off a month.
The BBC spent several days here: we visited 10 factories, spoke to four factory owners and more than 20 workers.
We were also in labor markets and with textile suppliers.
We discovered that the lifeblood of this empire is a workforce that sits at sewing machines for about 75 hours a week, in violation of Chinese labor laws.
These hours are not unusual for Guangzhou, an industrial hub for rural workers in search of higher incomes; or in China in general, which has long been the undisputed factory of the world.
But they belong to the ever-growing list of questions about Shane, a once little-known company founded in China that became global fashion monstrosity in a little over five years.
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Still privately owned, it is estimated to be worth around $60 billion, and is now eyeing a listing on the London Stock Exchange.
Its meteoric rise, however, has been tarnished by controversy over the treatment of workers and allegations of forced labor.
Last year, Shane admitted to finding children working in his factories in China.
The company declined a request for an interview, but told the BBC in a statement that it was "committed to ensuring fair and dignified treatment for all workers across its supply chain" and was "investing tens of millions of dollars in strengthening governance and compliance."
She added: "We strive to set the highest standards of payment and require all supply chain partners to adhere to our code of conduct. Furthermore, Shane works with auditors to ensure compliance with all regulations."
Shane's success lies in volume - his online inventory numbers in the hundreds of thousands - and huge discounts: dresses for 12 euros, sweaters for seven euros, prices that average under 10 euros.
Revenues have skyrocketed, surpassing names such as H&M, Zara and Britain's Primark.
Discount sales make places like Shane's Village, home to about 5.000 factories, most of which are Shane's suppliers, possible.
The buildings are stripped bare from the inside to make room for sewing machines, rolls of textiles and bags full of textile waste.
The doors of their basements are always open for a seemingly endless cycle of deliveries and pickups.
As the day progresses, the shelves fill with transparent bags labeled with the now recognizable five-letter noun that originates from various warehouses.
But even after 22:00 p.m., the sewing machines - and the people hunched over them - don't stop working as more textiles arrive, in trucks so full that the spools of colorful fabric sometimes roll onto the factory floor.
"We usually work 10, 11 or 12 hours a day," said a 49-year-old woman from Jiangxi who did not want to give her name.
"We usually work about three hours less on Sundays."
She's in a side alley, where dozens of people are huddled in front of rows of billboards.
They read the job postings on the board, while studying the seams on a pair of chinos draped over it.
This is Shane's supply chain.
Factories are hired to make clothes to order - sometimes small, sometimes large.
If chino pants become a hit, orders will skyrocket, and so will production.
Factories then hire temporary workers to meet the demand that their permanent staff cannot meet.
A migrant worker from Jiangxi is looking for a short-term contract - and chino pants are one of her options.
"We earn very little. The cost of living is very high now," she says, adding that she hopes to earn enough to send money back to her children who live with their grandparents.
"We're paid piecework," she explains.
"It depends on how heavy the item is. Something simple like a T-shirt costs one or two yuan [less than a dollar] a piece, and I can make about a dozen in an hour."
Studying the seams on chino pants is key to making that decision.
All around her, workers calculate how much they will be paid for each piece of clothing and how much they can make in an hour.
The alleys of Panyu function as labor markets, filling up every morning as workers and scooters speed past carts with morning dumplings, cups of hot soy milk, and an optimistic farmer selling chicken and duck eggs.
Standard working hours appear to be from 08:00 until well after 22:00, the BBC has discovered.
That's according to a report by Swiss advocacy group Public Eye, based on interviews with 13 textile workers in factories that make Shane's clothes.
They found that a large number of workers were working significantly longer than standard working hours.
The report notes that the basic overtime wage is 2.400 yuan (320 euros) - below the 6.512 yuan that the Asian Factory Wages Association claims is necessary for a "living wage".
But the workers we spoke to manage to earn between 4.000 and 10.000 yuan a month.
"These working hours are not unusual, but it is clear that they are illegal and violate basic human rights," says David Hatchfield of the group.
"It's an extreme form of exploitation and it needs to become visible."
The average workweek cannot exceed 44 hours, according to Chinese labor laws, which also state that employers must provide workers with at least one day of rest per week.
If a worker wants to extend those hours, it should be for special reasons.
Although Shane's headquarters are now in Singapore, there is no doubt that most of its products are made in China.
And Shane's success attracted the attention of Washington, which became increasingly suspicious of Chinese companies.
In June, Donald Trump's pick for US Secretary of State Marco Rubio said he had "major ethical concerns" about Shane's "deep ties to the People's Republic of China": "Slave labor, sweatshops, and trade tricks are the dark secrets behind Shane's success," he wrote.
Not everyone would agree with Rubio's choice of words to describe working conditions at Shane's suppliers.
But rights groups say the long working hours, which have become a way of life for many in Guangzhou, are unfair and exploitative.
Machines dictate the rhythm of the day.
Breaks are only taken for lunch and dinner, when workers, with metal plates and chopsticks in their hands, line up in the canteen to buy food.
If there are no more places to sit, they stand on the street.
"I've been working in these factories for over 40 years," said one woman who spent just 20 minutes eating her meal.
This was just another ordinary day for her.
Inside, the factories we visit are not overcrowded.
There is enough light, and industrial fans have been brought in to cool the workers.
Huge posters urge staff to report underage workers - most likely a reaction to the discovery of two cases of child labor in the supply chain last year.
The BBC concluded that the company had begun to control suppliers more closely ahead of plans to list on the London Stock Exchange.
"The bottom line here is their reputation," says Sheng Lu, a professor of fashion and apparel studies at the University of Delaware.
“If Shane can successfully achieve an Initial Public Offering (IPO), then it means they are recognized as a decent company.
"But if they want to maintain investor confidence, they need to take at least some responsibility."
One of the biggest challenges Shane faces is accusations that he sources his cotton from the Chinese region of Xinjiang.
Once considered one of the finest fabrics in the world, Xinjiang cotton has fallen out of favor after accusations that it is made using forced labor. people from the Muslim Uyghur minority, and Beijing persistently denies this accusation.
The only way to avoid this criticism is to be more transparent, says Professor Sheng.
"If you don't publish a list of all the factories, if you don't make your supply chain more transparent to the public, then I think that's going to be a pretty big problem for Shane."
A big advantage, he adds, is that Shane's supply chain is in China: "Very few countries have a complete supply chain at home. China has it - and no one can compete with that."
Ambitious rivals such as Vietnam and Bangladesh import raw materials from China to make clothes.
But Chinese factories rely entirely on local sources for everything from fabric to zippers to buttons.
So it's easy for them to make a variety of clothes and they can do it quickly.
And this is especially beneficial for Shane, whose algorithm determines orders.
If customers click on a dress again and again or spend a long time looking for a wool sweater, companies know to ask factories to make more of them - and quickly.
For workers in Guangzhou, this can be a big challenge.
"Shane has its own strengths and weaknesses," one factory owner told us.
"The good thing is that the order is ultimately large, but the profit is small and fixed."
Shane, given his size and influence, is a tough negotiator.
And so factory owners have to cut costs elsewhere, which often results in reduced wages for staff.
"Before Shane, we were producing and selling clothes ourselves," says the owner of three factories.
"We could estimate costs, set a price, and calculate profit. Now Shane controls the price, and you have to think about ways to reduce costs."
When orders peak, however, it's a golden thread.
The company ships an average of about one million shipments per day, according to data from ShipMatrix, a logistics consulting firm.
"Shane is a pillar of the fashion industry," says Guo Qing E, a supplier to Shane.
"I started when Shane started. I witnessed his rise."
“To be honest, Shane is a fantastic company in China.
"I think he'll only get stronger because he pays on time. That's where Shane is most reliable."
"If our goods arrive for collection on the fifteenth of the month, regardless of whether it's millions or tens of millions, the money will be paid on time."
Shane, with his hard working hours and sometimes lower wages, may not be a source of comfort to all of his workers.
But it is a source of pride for some.
"This is the contribution that we as the Chinese people can make to the world," says a 33-year-old supervisor from Guangdong, who did not want to be identified by name.
It's dark outside and workers are lining up to return to the factories after dinner for the last leg of the workday.
She admits that the working hours are long, but "we get along well with each other. We're like one big family."
Hours later, when many workers head home to sleep, the lights in several buildings remain on.
Some people work until midnight, one factory owner tells us.
They want to make more money, he says.
After all, in London, Chicago, Singapore, Dubai and many other places, someone is on the hunt for the latest bargain purchase.
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