The transaction was quick and uncomplicated. There wasn't even any haggling over the price. In the remote southern Sudanese town of Manyiel, a Muslim trader eagerly accepted a stack of currency worth about $1,000. Moments later, he delivered the mercha ndise--a pair of slaves.

The story is not out of some 19th century novel. It is from the account last week by two Baltimore Sun journalists, Gilbert Lewthwaite and Gregory Kane, of their trip in April to the Sudan to see if they could buy a slave. The enslavement of human bein gs and the buying and selling of them are said to be common in the Sudan. But always the charges are denied by the government. The Sun's project got a boost when Minister Louis Farrakhan, head of the U.S.-based Nation of Islam, defended his own controvers ial trip to the Sudan by challenging reporters to find evidence that slavery exists in the largest and poorest nation in Africa. "Where is the proof?" Farrakhan demanded in a speech to the National Press Club in March.

The Sun editors proposed to get the proof, but the reporters had misgivings at first about going through with the actual purchase of a slave. The plan, of course, was to free anyone who was bought. But was it ethical? In the articles he later wrote, Ka ne, who is black, pointed out that 19th century abolitionists bought freedom for thousands of slaves in the U.S. In the final analysis, says Sun foreign editor Jefferson Price, the decision was pragmatic. "Rather than get the story from people who c laimed that they had been treated as slaves," he says, "we thought that if we actually made the purchase ourselves, it would present incontrovertible proof that the system did exist."

The reporters arranged for their journey through Christian Solidarity International. A Swiss group, it has been ransoming Sudanese slaves, and agreed to fly the journalists into Sudan secretly. As they would learn on their week-long trip, the traffic i n humans is an outgrowth of a vicious, decade-old civil war between the Muslim north and the Christian and animist south that has killed hundreds of thousands. Much of the fighting on the government side is conducted by unpaid local militias, and the radi cal Islamic regime in Khartoum allegedly encourages soldiers to compensate themselves through looting. The most valuable war booty is women and children.

Thousands of southerners have been abducted and put to work in households and farms in the north, according to Human Rights Watch/Africa and Amnesty International. The women are frequently forced to become "wives" to their Muslim captors. At the same time, the Sudanese People's Liberation Army, which leads the southern rebellion, has been accused of forcibly inducting local youths into its ragtag army. Over the years a flourishing commerce has built up, with middlemen buying slaves and resell ing them to new masters or back to their families.

Accompanied by British baroness Caroline Cox, who works for Christian Solidarity, Lewthwaite and Kane were flown by a bush pilot from Nairobi to the steamy town of Nyamlell in southern Sudan. They were warmly greeted by rifle-toting Dinka tribesmen, ma ny of whom told harrowing tales of their own enslavement and escape. The next day Cox brought word that a trader had arrived in Manyiel, a three-hour walk away, with a dozen children he had apparently purchased farther north.

The reporters set out with an armed escort next morning. Shortly after arriving, they were approached by the trader, who called himself Adam el Haj, and insisted that his only motive was to foster peaceful relations between his northern tribe, the Rizi egat, and the Dinka by returning Dinka children. The reporters surveyed the youngsters Haj showed them and finally picked the oldest, Akok Deng Kuot, 12. It turned out that his half-brother Garang, 10, was also among the captives; Lewthwaite and Kane boug ht them both. The reporters handed them over to their overjoyed father, who had been alerted that his sons, who had been captured seven yeras before during a raid on their village of Mayak, had been freed.

The boys told how they were tied on the backs of horses and taken to the north, where they ended up working on adjacent farms whose owners were relatives. "I was given to a very bad man," Garang told the reporters. "He always made me do difficult things like carrying away hot ashes. Sometimes I was beaten." Akok said his main job was cleaning up cow dung. The bruised and malnourished boys claimed they lived on sour milk and table scraps and were tied or locked up at night.

The Sudanese government responded to the three-part Sun series by insisting that holding prisoners for ransom is a centuries-old practice not condoned by Khartoum. The Sun concluded the opposite and called for international sanctions against Sudan. As for Farrakhan, the paper tried to get his comment on the story, but he never returned its calls.