Economists point to the fluidity of capital as a driving force in global markets. Capital respects no borders or nationalities. It flows wherever investment promises to deliver a handsome return.

Human beings, unfortunately, float - and sometimes drown - in its wake. Ever since I began writing a book on human slavery in our own time (see announcement on sidebar), I have met some of those characters. Here's one of those encounters.

Not long ago I went to London and stayed in a hotel in the city center. One evening I noticed that a member of the hotel staff who served me a cup of tea in the lobby was distraught. Her eyes betrayed a recent cry, and she was stumbling through her work. I asked after her well-being, and she answered quickly, "Life is terrible, but I can't talk about it." I let her be.

The next evening, as I was again relaxing in the lobby, Katja came over to my table to thank me for my concern the night before. She went on to share her remarkable story.

Katja is from Poland and had been in London for only eight months. She had to leave Poland for her own safety. The local mafia had murdered her father because he would not cooperate with a corruption racket they were running in Warsaw. She knew the identity of the man who pulled the trigger because he continued to threaten her family after the murder. Katja bravely turned him into the police and a high-profile court case ensued. She subsequently appeared on television many times to denounce the stranglehold that criminals and corrupt police officers had on Polish society.

Sadly, her efforts were like trying to slow a mighty stream with a single stone. Her father's killer was found innocent, and the local mafia had her number. She fled to London and considers herself lucky to have found a job in an upscale hotel. Life is expensive in London, so Katja shares a flat with several other East European girls with whom she ekes out an existence.

Due to her own hardship, Katja was not thrilled when her younger brother called her from Warsaw and said that he was going to join her in the U.K. Katja warned him that opportunities were scarce in London for a Polish immigrant. "Don't worry," he said in an effort to soothe her anxiety. "I already have a job in a factory."

An advertisement in a Warsaw paper had promised good pay for Polish workers in Birmingham. A broker's fee of $500 and airfare were required, so her brother borrowed the money from their mother. He made the trip with a dozen other young Polish men.

The "broker" picked the young men up at Heathrow and piled them in a van. They drove directly to Birmingham, and at nightfall the broker dropped the whole crew off at a ramshackle house inside the city. He ordered them to be ready to be picked up in the morning for their first day of work. A bit dazed by the pace, they stretched out on the floor to sleep.

Their rest was brief. In the wee hours of the night, the broker returned with a gang of 10 or so thugs armed with cricket bats. They beat the young Polish boys to a pulp and robbed them of all their valuables. Katja's brother took some heavy kicks to the ribs and head, then stumbled out of the house. Once outside, he saw two police cars parked across the street. The officers in the cars obviously chose to ignore the mayhem playing out in front of their eyes. Katja's brother knew better than try to convince them otherwise; the police in Poland would act no differently. Who knows, maybe they were part of the broker's scam. Or maybe they just didn¹t care about a bunch of poor Polish immigrants "invading" their town.

The day I first saw Katja, she had just received a call from her frantic brother in Birmingham. In many ways, they were fortunate. Human trafficking thrives in the new global economy. People cross borders, are told by their "brokers" that they have to pay off their debt ‹ for rent, food, transport from their host country ‹ and end up serving for years as indentured slaves. The police and other local authorities often share in the revenue.

Money does not flow evenly in global markets. It accrues in select pockets and creates both opportunity and exploitation. We must pay close attention to the names and faces of those who are most vulnerable to its flow and be prepared to rescue them from drowning in it.

*Originally published in the June issue of Sojourners magazine