In the first of a two-part series, Thailand correspondent Tan Hui Yee looks at the labour issues that expanding opportunities have brought to Mae Sot on the Thai-Myanmar border.
Mae Sot - She was always careful to stay in the shadows, carrying her shoes and slippers into her factory dormitory instead of leaving them at the door, and cooking meals indoors.
Ms Malar Aye, 33, was an illegal worker. The Yangon native had slipped into the Thai border district of Mae Sot and found work easily among factories there.
But her average wage of about 130 baht (S$5.20) a day was less than half of what was paid in Bangkok, spurring her decision to leave.
"I planned to 'take the jungle way' to Bangkok," she says, referring to the route used by human smugglers.
Then the Thai military seized power on May 22 last year and expedited the registration of undocumented workers.
This move pushed at least one million more migrant workers into the system.
The registration documents that Ms Malar Aye obtained put her Bangkok dream within easy reach, if not for one problem.
Her employer was hanging on to one of her documents.
He would not let her go.
Industries feeling heat
Mae Sot is one of the busiest gateway districts in South-east Asia's second-largest economy.
It is also an industrial base fuelled by an estimated 300,000 workers out of the two to three million migrant workers countrywide.
According to the Thai Immigration Bureau, almost 25,000 people from Myanmar used short-term border passes to enter Thailand via Mae Sot last February.
The actual arrival numbers are far higher.
Crossing the Moei River - the boundary between the two countries - is a 20-baht, five-minute affair on a boat.
On any given day, hundreds of young Myanmar workers disembark at unofficial landing points, disappearing into the cluster of bamboo and concrete shacks that form migrant villages on the water's edge.
But the garment and food processing factories that rely on such abundant and cheap labour are feeling the heat.
While a nationwide 300-baht daily minimum wage scheme implemented in 2013 has drawn attention to regional pay gaps, the state's latest effort to register migrant workers is promising to give them feet.
Industrialists are wary that even more workers may leave for higher-paying jobs elsewhere in Thailand and some - like Ms Malar Aye's employer - are resorting to questionable means to make them stay.