Valentino, usually so quick to smile and impossible to discourage, was weighed down those days in Marial Bai. His expression was very serious, and though he spent a good deal of time among his family and the people of the town, he often retreated into the Save the Children compound for hours at a time - overwhelmed by the demands made upon him, the people who wanted his attention. He couldn't believe the poverty. There was almost no livestock, and the homes, all made from mud and thatch, were small, temporary-seeming. We visited the hospital, one room resembling a cement bunker, where eight dilapidated beds were arranged. There were no windows, no sheets, no pillows, no doctors - there was only one man who dispensed medicine. The hospital's two patients, two women sitting on a bed, each with a baby on her lap, glared at us until we left.

The civil war has reportedly killed two million people, though the majority of those have died of starvation and disease. People could not farm because they didn't know when they would have everything taken from them - their fields burned, their livestock stolen. Schools opened only occasionally. With uncertainty the guiding state of mind, the war had effectively put life in Sudan on hold for 20 years.

It is a terrible emblem of desperation that people in any number of troubled countries have wished for, and in some cases continue to wish for, American military intervention in their affairs. When Valentino and I were biking on the airstrip one night, we heard a commotion by the Concern compound. We rode to the noise, and soon could make out a television - there were only a few televisions for perhaps a hundred miles - set on a table, outside, being powered by a generator. We dropped our bikes and joined the crowd of about 15 young Sudanese men watching CNN.

"What happened?" we asked one of the men.

"They caught him," he said.

On the screen was the wretched face of Saddam Hussein, in his post-arrest mugshot. He looked haggard and half dead and crazed, and his capture was seen, by the assembled men, as a very good sign.

"Next is Khartoum," one man said.

To them it meant that not only could American military might topple a murderous government in short order, but American and British soldiers could search out, find and bring to justice the dictators who oppressed their people.

And though the elders of the town had more realistic expectations of the US, they still put great faith in the west to bring them hope. On one of our last days in Marial Bai, Valentino and I met with the commissioner of the region, who attributed the peace process, then under way, to the suffering of the Lost Boys, and the Americans' awareness of their plight. He then put it to Valentino: "Now that you're an American, what will you be doing with your life?" This tipped the guilt Valentino already felt.

He decided then that, though his life had been epic in the scale of its sorrow and deprivations, he had been lucky. Those who had stayed in southern Sudan during the war were far worse off. Once at the refugee camps, he knew he would be fed, he would be safe (most of the time), he would be educated. Those who had stayed in Marial Bai had no such guarantees.

When we returned from Sudan, Valentino and I were more committed than ever to getting his story into print as soon as we could. In an attempt to kickstart the writing of the book, I published an account of the trip in journalistic form in the Believer magazine. The exercise made clear, though, that my telling of Valentino's story, in my voice, would be distracting and tonally incorrect. In the account I wrote, I was present, both as narrator and as the guy riding in the cargo hold next to Valentino; there was no way to excise myself from the story. But in the book, I knew I had to disappear completely.

The first decision made that spring was to have Valentino narrate his story. His voice was so distinctive and powerful that any other way of telling it would be criminally weak by comparison. But my standards for what would qualify as non-fiction were strict; as a journalist, I was trained not to put any dialogue between quotation marks unless it was on tape. We had no such thing, and Valentino couldn't remember who said what at almost any point in his life, and thus the book would be without any dialogue at all.