The man at the head of the line of figures emerging out of the desert in southern Sudan is called Ahmed. At least that is the name he chooses to use.
The people walking behind him are slaves, all 386 of them. They are Dinka people, who were rounded up by Ahmed and his associates. Ahmed's face is partially covered because he does not want to be recognisable when I take his photograph.
I witnessed this strange sight just a few weeks ago in Bahr el Gazal province in southern Sudan, an area where the people have to cope increasingly with the effects of hunger as well as war and the slave-traders.
The traders come from the north and are mostly Arab. Countless thousands of people from southern Sudan have been abducted by the traders and forced into slavery. They work, without pay, on Arabrun farms and homes in the north of the country.
Many are ill-treated; women may be subjected to genital mutilation and forced into concubinage.
The Sudanese government denies that slavery exists in Sudan, insisting that abductions are the result of "tribal conflicts". However, since 1995 a Swiss-based human rights group, Christian Solidarity International, (CSI) has been paying Arab traders large sums of money to recover Dinka slaves from northern Sudan.
With CSI, I was taken to a place to which 203 slaves have been brought by an Arab trader called Noor. The slaves were herded into a large group and stood before us.
John Eibner of CSI sought to allay any anxiety. "We're here to make sure you are free," he told the slaves, "free to go back to husbands, sons, mothers and fathers. No one should be afraid. We come in peace."
And with that the transaction began. Noor was paid £10,000 to free the slaves; I paid $210 to free a 21-year-old woman, Nyamada Deng, and her two children aged eight and three months.
Nyamada said she was captured in 1986 during a raid on her village in which her father died. After being marched for seven days with her hands tied behind her back, she was put to work in the kitchen of an Arab man's house.
Nyamada is now free, but southern Sudan remains a dangerous place to live. Yesterday aid workers returning from remote parts of the region reported that government cavalry had launched brutal attacks on rebel villages.
They said dozens of civilians, mainly from the Dinka tribe, had been killed in the raids which began early this month in Bahr el Gazal.