But after that first year of interviews and my first attempt to assemble the resulting narrative, we both realised that there were great limitations, in this case, to the oral history model. Valentino was six years old when he left his home and began his 800-mile journey to Ethiopia, and thus his memory of that time was very spotty. When we looked at what we had from our recording sessions, it was fascinating, but it did not transcend the many human rights reports and newspaper articles already available to the world. It was clunky, spare, and full of holes. In addition, a new book called They Poured Fire On Us From the Sky had just appeared, and it did much of what we had originally intended to do: it wove together the oral histories of three Lost Boys, and did so with great skill.

But though the form of the book was still unclear, I knew that we would have to return to southern Sudan, to Valentino's hometown of Marial Bai, if either one of us hoped to tell the story with any degree of accuracy. With the help of Mary, we secured a visa for Valentino to travel to Nairobi, and once there, I went about calling relief agencies working in southern Sudan, hoping to find a few seats on any plane flying into the region. Through a series of lucky phone calls, I was able to find an aid agency, Concern, that was willing to let us fly in the cargo hold of a plane that was dropping supplies throughout the south.

So, in December of 2003, Valentino and I travelled amid the bicycles and medicine and food of a humanitarian aid flight, the plane making four stops in the country along the way. When finally the plane was on its way to Marial Bai - there is a dirt airstrip that bisects the tiny town - the plane was empty, excruciatingly loud and Valentino's head throbbed from myriad pressures. He hadn't seen his parents since he was six, and didn't recognise the landscape as we descended. "My heart is beating!" he said, as the plane lowered its landing gear. He would be the first Lost Boy to return.

When Valentino stepped off the plane and on to the dusty dirt runway, he was quickly surrounded by easily a hundred people, moving in from all sides, calling out Achak, his given name. After a few seconds, an old man, frail and toothless, found his way through the crowd and put his hand on Valentino's shoulder. He spoke into Valentino's ear and they embraced. They pulled away from each other and Valentino looked into the old man's eyes and smiled. "Hey," Valentino said over the throng, grinning widely. "This is my father." After this brief reunion, which lasted no more than a minute, Valentino's father walked off. They would meet later, privately.

As the plane's cargo was unloaded and the Russian pilots climbed back into the cockpit, the crowd began to walk away from the airstrip and towards the village. Through the settling dust a violet-clad woman of about 60, weathered and very tall, with small hard eyes and a thin straight mouth, approached Valentino shyly. "Achak," she said to him quietly. "I am your mother."

She held his face in her hands. Valentino yelled over the crowd - and again without fanfare - "Hey! This is my mother!"

They walked arm in arm for a few yards and through a corrugated metal door separating the runway from the compound run by Save the Children, which agreed to give Valentino and his family a degree of privacy. He walked through with about nine of his friends and relatives, his arm around his mother, whose head was on his shoulder, whose hand was on his heart. With tears in her eyes, she stared at Valentino in plain astonishment. "Is it really you?" she said to him again and again. Soon she left, with plans to meet him later in the day. Once she was gone and the other visitors had departed, Valentino tried to smile but was clearly burdened. "She has been very sick," he said. "She will not live very long. She was afraid that she would die before seeing me again."