The pitch was like a dream come true. For $3,000 each, the three desperate young Indonesian women would receive falsified visas, airline tickets from Jakarta, and restaurant jobs when they got to New York. A man named “Johnny” would meet them at the airport and arrange their housing.

But once the women got off the plane, it didn’t take long to see that Johnny had other ideas. He and his friends hustled them off to brothels, first in Connecticut and then in Brooklyn, while threatening to shoot them if they refused to be prostitutes. Over four lurid days, the women were repeatedly forced to have sex with men who paid their captors $140 for each 45-minute period. Johnny also told each woman that she owed him $30,000, and he started making arrangements to “sell” them to other brothels in New York and Boston.

As this case suggests, the sordid business of human trafficking, which includes enslavement in agricultural work, sweatshops, domestic labor, and prostitution, is rapidly expanding. And with its growing immigrant population, experts say, parts of New York City, including Brooklyn and Queens, have become hot spots in a trade that the International Labor Organization has described as the “underside of globalization.”

The State Department recently estimated that close to 700,000 people are moved through the global networks of human trade each year, and some officials believe that as many as 50,000 of those people are brought to the United States. And while authorities are trying to staunch the flow—“Johnny” and two of his confederates pleaded guilty to federal slavery charges last fall—critics say that the crackdown on visa violators since the 9/11 terror attacks has made it harder to get victims and witnesses to come forward to talk about the slave trade.

“It is incredible how big of a business it is,” said Christa Stewart, the director of Safe Horizon, a Manhattan-based nonprofit organization that has expanded its outreach from domestic violence victims to women who have been enslaved. She and other advocates said a fundamental tragedy of this crime is that the victims, like the Indonesian women who initially were trying to change their lives, were hopeful and courageous enough to leave everything behind in search of a new life.

Although there are many cases of domestic servitude, in which the victims are locked up and forced to be maids and cooks, women are particularly vulnerable to sexual enslavement. Ovita Williams, who runs the victim counseling services at the Kings County district attorney’s office, explained that women are more often enslaved than men because of their lower social standing in many cultures and the ease with which they can be hidden from society. “As women, we are subjugated in just about every country,” Ms. Williams said.

Jennifer Moore, the assistant United States attorney in Manhattan responsible for the case of the three Indonesian women, has prosecuted and investigated several trafficking cases. Moore said prosecutors and agents are seeing “women circulated in between networks of brothels.” These networks constantly shift and trade women in different cities. She said law enforcement is seeing trafficking networks that are often organized around specific nationalities, making it very difficult for investigators to do undercover work. Customers are typically admitted by race or ethnic background—for example, only Chinese men are allowed into brothels with Chinese women. The distinctions are so tightly made, she said, that even a Puerto Rican undercover agent would not be able to go to a brothel with Mexican women.

To stop the slave trade, Congress passed the Victims of Trafficking and Violence Protection Act in the fall of 2000 which made trafficking a federal crime. The law also made victims eligible to receive federal aid, like counseling services and Medicaid coverage. Since then, the U.S. Attorney’s Office in Manhattan has been working with state and local law enforcement officials to coordinate investigations in the New York area.

As Moore described it, local vice squads conduct raids on brothels, and if they feel it is potentially a trafficking situation, they contact the U.S. Attorney’s office along with a number of nonprofit organizations that counsel the victims and help them secure shelter, health care, and, ideally, proper immigration status.

However, “implementation has been problematic,” said Juhu Thukral, Director of the Sex Workers Project. Part of the Urban Justice Center, it is one of the major organizations assisting victims of trafficking. Post-9/11 reorganization of federal agencies that deal with immigration issues and their shift into the new Department of Homeland Security, has created confusion. “Obviously, it’s the same people,” Thukral said. “But it is a question of who is handling what.”

Stewart, of Safe Horizon, said the much tighter enforcement of immigration laws “has been a real chill for people to come forward.” Traffickers, Stewart said, often tell their victims that they should be afraid of the police because they could either be deported or thrown in prison. Stewart points to large industrial parts of Brooklyn like Red Hook and Sunset Park as showing up on the trafficking radar as well as southern areas such as Brighton Beach and Coney Island, where organized criminals from the former Soviet countries have a tight grip. However, due to the clandestine nature of these crimes, local experts are frustrated with the lack of exact numbers or clear statistics.

For many of the nonprofits and local authorities, the largest problem is reaching out and finding victims of trafficking. “The biggest challenge is you hear these statistics, 50,000 people, and where are they?” says Suzanne Tomatore, Program Director of the Immigrant Women & Children Project, part of a nonprofit legal defense fund that represents victims of trafficking called the Association of the Bar of the City of New York Fund. Many of the nonprofits have focused on community outreach and teaching police officers how to recognize victims of trafficking. Still, Tomatore said, “in terms of accessing services, it’s almost like where domestic violence was 20 to 30 years ago.”

Charles J. Hynes, the district attorney in Brooklyn, also has tried to heighten awareness of trafficking. As part of an overall campaign to combat prostitution, Brooklyn has started what it calls the “John School.” Men caught with prostitutes are required to attend a class on the dangers and abusive nature of sex work or face 90 days in jail. Like similar programs in cities across the country, Brooklyn’s version puts first offenders face to face with former prostitutes, law enforcement officers, and nonprofit workers who describe the dark side of prostitution, including sexual enslavement. The results, officials say, have been very positive.

Even though Kofi Annan, the Secretary General of the United Nations, has identified trafficking as a “worldwide plague,” many developing countries are too overwhelmed and impoverished to do much to stop it. The State Department has instituted a penalty system, withholding certain kinds of aid money from countries that have poor records on human trafficking. Still, everyone recognizes that the only hope lies in greater cooperation. Both Williams, the Clinical Services Director in Mr. Hynes’s office, and Moore, the Federal Prosecutor in Manhattan, have met with officials from countries throughout Asia, Europe, and South America, to talk about how they can work together.

Law enforcement officials said that the three Indonesian women arrived in New York in June 2001. After three weeks of being held captive and guarded at all times, two of them crawled out of a window of the Brooklyn brothel at dawn. Police raided the house, at 705 54th Street, the next night. “Johnny,” whose real name is Chai Hock Ng, pleaded guilty last September to violating the Mann Act, the Progressive Era white slavery law. He had already been held for months without bail, and including time served, he spent just over a year in jail.

Like so many others, the women had stumbled into this world by paying a fee to a woman in their home country who purported to be a travel and employment agent. Often, officials said, the agents are women, trusted friends of the family who recruit new workers by telling them “success” stories of others they have helped. Unfortunately, the case of the three Indonesian women was exceptional—two of them managed to break free from their captors and seek help.