She was halfheartedly helping out in her parents' grocery store in Bangkok, daydreaming of an office job that would let her wear pretty clothes, when evil entered her life in the form of a man who made her an irresistible offer He would arrange her passage to the United States and a job, he said, and it wouldn't cost her a cent, because her future employer would pay his commission.

Within days, the 23-year-old Thai woman, who asked that she be identified only by her nickname, Na, was in New York.

In New York, and caught in a nightmare of sexual slavery, an ordeal so hideous that even months later, as she described it in the downtown Manhattan office of the immigration agents who helped save her, her head dropped in shame, and she doodled unconsciously right on the government tabletop.

Almost as soon as Na arrived last September, she was informed of the real, Faustian terms of her passage to New York. To pay off the people who had bought her ticket and arranged her visa, she was expected to have sex with more than 300 men. She would be held captive behind the locked doors of a Chinatown brothel where, she later learned, the bars covered the windows and buzzer-operated gates controlled the doors. She would not be allowed to leave the building until she had worked off her debt.

'I could not respond, but I wept,' Na recalled through an interpreter. 'I thought 'I can't do anything. I'm in their hands.' '

The United States is not the usual destination for international traffickers in human flesh, who mostly feed the thriving sex industries in Thailand, the Philippines, Japan and India. But experts say the scale of the operation that used Na - a brothel at 208 Bowery housing more than 30 smuggled Thai women - indicates that thousands of Asians could be engaged in forced prostitution in America.

Illegal brothels like the Bowery's, which the police closed down in November, have surfaced in recent months in Los Angeles, Seattle and San Diego. Rarely, however, have the workings of an American den of forced prostitution been broken open as thoroughly as they have in Na's case. Its details were exposed in the records of one trial completed in June and more trials are now under way.

'This is a classic case,' said Kathleen Barry, a professor at Pennsylvania State University, founder of a group called the Coalition Against Trafficking in Women and author of Prostitution of Sexuality (1995 New York University Press), which includes a broad study of the international trade in prostitutes.

'Everything that goes on in the sex industry appears in this case,' she said 'From the specific exploitation of an individual woman when the customer buys her, to the systematic slavery of selling her and other women through fraudulent schemes, to the disparity between the economic conditions in Thailand and in this country.'

At the United Nations Conference on Women in Beijing, Dr. Barry's allies called for a worldwide network to combat prostitution, in part by coming down harder on customers and pimps.

Officials of the United States Immigration and Naturalization Service and the New York police say they share the women's concern about forced prostitution. 'It's almost in the nature of what we have seen in alien smuggling, because of the high cost for people coming in,' said Daniel Molerio, the immigration agency's assistant district director for investigations, who supervised the raid on the Bowery brothel. 'You are going to find many cases of people held against their will.'

Like recent kidnapping and murder cases attributed to Asian gangs, including the death of a Chinese woman in Brooklyn two weeks ago, forced prostitution typically involves Asian organized crime and smuggling rings, said Russ Bergeron, a senior spokesman for the immigration agency. 'We have seen major criminal organizations utilizing this type of enterprise,' he said.

In a recent case involving an interstate chain of massage parlors staffed by Asian women forced into sex, Mr. Bergeron said 'The network was very sophisticated. These women were provided with false documents, false I.D.'s, and they were even rotated from city to city periodically in order to defeat law enforcement efforts.'

Coerced prostitution of foreign women is especially difficult to combat, officials said, because of its usual secrecy and the profit that drives it. And even once detected, it can be hard to prove because the prostitutes often fear revenge and deportation.

'Ms. Adkins started to accept

indentured women from Thailand,

she said, and her suppliers told

her not to let them outside

because they might run away.'

'You can't force them out of the business,' said Lieut. Peter Martin of the New York Police Department's Vice Squad, which helped with the Bowery case. 'Unless we have even a mere suspicion that they're held against their wishes, we can't take any action.'

In Na's case, the harbingers of freedom were city inspectors who, knowing that the upper stories of 208 Bowery were used as a brothel but finding it hard to keep it closed down, went looking last year for housing code violations that could close it another way.

Checking the premises on Oct. 11, 1994, they encountered 2 women - among 31 present - who made clear in broken English that they wanted to leave. That brought a visit from the police and interest from immigration officials, but the other women followed their bosses' orders to stay put and keep quiet.

On Nov. 8, a prostitute who had managed to escape phoned and told the captives they could appeal for help by calling 911. In the police raid that followed they arrested the madam, Siew Geok Adkins, better known as Lilly Chan or Jenny, along with the bouncer and several others. Six more women turned themselves over to authorities; the rest were let free - two of them only to turn up weeks later in a similar situation in Seattle.

Immigration agents in on the raid said they found rows of cubicles and whole cases of condoms.

Since then, the case has brought together more than a dozen defendants, from brokers in women to their buyers, and slowly unfolded the ugly inner workings of a modern international slave trade.

Joseph Morales, the bouncer who stood guard at the door, has been convicted of kidnapping and civil rights violations, and faces sentencing on Oct. 30. He could receive 10 years in prison.

Many women held at 208 Bowery first claimed they had been lured to the United States with promises of restaurant jobs. Then several changed their stories, admitting they had known they would be working as prostitutes, but had thought they would be free to come and go. Authorities said the still had some doubt about Na's story, but she maintained she would never have willingly become a prostitute.

Ms. Adkins (Lilly Chan), who turned state's witness at Mr. Morales's trial this spring, described the cold-blooded details of overseeing a stable of sexual slaves.

Beginning in 1993, when her regular supply of Korean, Taiwanese and Hong Kong prostitutes began to dry up, Ms. Adkins started to accept indentured women from Thailand, she said, and her suppliers told her not to let them outside because they might run away.

From early 1994 until the brothel was closed down, she obtained about 50 Thai women that way, she testified. After one escaped by jumping out a second-story window, she installed iron bars, she said. Three buzzer-operated gates controlled the doors, and the women were herded into a secret basement during several police raids.

'What does it take for a woman to jump out a second-story window?' Assistant Attorney Tai Park, who helped in the Federal prosecution of Mr. Morales, wondered, openly appalled. 'What does it take for an illegal alien who can't speak English to say to some white stranger, 'Can I go out with you?'

'What does it take, if not absolute horror at the restraint you have been confined to day after day?'

Customers paid a $30 admission fee and $100 for about an hour with a prostitute, Ms. Adkins said. The only money the women kept came from customers' tips. Some of the Thai women were so inexperienced that clients complained. The women generally worked from 11 am to 4 am every day, she said, and had sex on average with two men a night.

Along with marketing women who 'belonged' to other bosses, Ms. Adkins said she bought six or seven women outright. They cost $6,000 to $15,000, she said, calling the business very profitable. One woman whom she bought for $9,000 had to pay her back in 270 'quotas' - 270 men for $27,000. Other women had to repay their smugglers by having sex with 380 to 500 men, she said. All were charged $300 a week for room and board payable through sex with three more men.

'The Thai women were all

on tourist visas, obtained by

forging letters from companies

saying they were employees.'

The women kept track of how many men they had slept with in little booklets, Ms. Adkins said; she kept a master ledger as well.

But all that counting may have been pointless, Dr. Barry believes. In most cases of forced prostitution, she said, talk of debt is only a ruse, and the captors 'have no intention of setting the girls free until they're no longer usable.'

'If they get AIDS they'll be set free, or if they grow haggard,' Dr. Barry said.

The Thai man who enticed Na to America, Jawarit Sillaphanond, testified as part of his plea bargain that he had put several women in the brothel, lying to some that they would work in restaurants and to others that they would be prostitutes but free ones, able to choose their men and come and go. Once they were under his control, he threatened to hunt them down and hurt them if they escaped, he said. The Thai women were all on tourist visas, obtained by forging letters from companies saying they were employees.

Witnesses said Chinese and Vietnamese gangsters were also involved in the brothel, collecting protection money and hunting down escaped prostitutes.

Happily, Na's tale ends well. After the immigration agency got working papers for her and she found a job at a Thai restaurant, a patron fell in love with her and married her, she said. She plans to stay in America.

But still, when she thinks back on her time in the brothel, the lilting syllables of her Thai speech fill with unaccustomed rage.

'Every time I talk about it, I'm angry that it happened to me,' she said. 'They bought me something, and they wanted to use it to the full extent, and they didn't think that these people in there are human beings.' ;