The first glimmering of the writer's impulse that would become 23-year-old Uzodinma Iweala's novel came when he picked up a newsmagazine in the kitchen of his family's Potomac home and read an article on child soldiers in Sierra Leone.

Iweala was in high school at the time, at St. Albans. Born in Washington to Nigerian parents -- his mother had taken a job with the World Bank, and his father, a doctor, had followed -- he was a privileged teen with dual citizenship, not sure exactly where he belonged. As he read about children abducted by rebel bands and trained as killers, he thought: These kids are younger than I am.

He sat down and wrote a very short story -- not for school, just for himself -- then set it aside.

He moved on to Harvard, where, in his junior year, he helped bring in speakers to talk about conflict in Africa. One was a young woman from Uganda named China Keitetsi. She'd been just 8 years old when she was forced to fight in the civil war there and had lived to write a book about her brutalizing experience. When she finished telling her story, Iweala recalls, her stunned audience was completely silent.

"It almost made your heart stop," he says.

He hung around to talk with her afterward. Keitetsi asked what he was studying. English, he said, but his parents wanted him to go to medical school.

"Oh, really," she said. "Well, you know, I have no parents."

What could he say?

Looking back, he thinks perhaps "Beasts of No Nation" -- the title is from a song by Fela Kuti, one of Iweala's favorite musicians -- was his response.

Set in an unidentified West African country and written in an urgent, first-person voice, Iweala's book tells the story of Agu, a boy who's forced to become a soldier after his father is killed. He wrote it as his senior thesis, with novelist Jamaica Kincaid as his adviser. When it was done, Kincaid sent the manuscript to her agent, who found publishers for it in Britain and the United States. Like a veteran author, Iweala is now on his American book tour. Thursday he'll be at Vertigo Books in College Park.

All of which makes the first-novel thing sound much easier than it really was.

Across the stream, I am feeling in my body something like electricity and I am starting to think: Yes it is good to fight. I am liking how the gun is shooting and the knife is chopping. . . . I am liking to kill.

-- from "Beasts of No Nation"

The Potomac house is a brick Colonial on two partially wooded acres. It's got a swimming pool and a three-car garage, though it's modest by the standards of the neighborhood. The house has been "lived in, and lived in thoroughly," Iweala has written in a personal essay he's working on, and he goes on to mention the international art with which his mother has filled its rooms and the good times he's had scarfing pizza with friends during basement sleepovers.

Yet his parents told him "always to think of himself as Nigerian first." And the Potomac house has never felt entirely like home.

He's in the living room now, just back from spending time in Nigeria, where he's been working with refugees and where his mother became the finance minister a couple of years ago. Soft-spoken and polite, he seems not yet used to the attention he's started getting. Last summer, in London, his agent introduced him to a bearded man sitting in the office. "Uzo, meet Salman," Iweala remembers her saying, "and I was like -- no."

"He's ridiculously young," Salman Rushdie later told Dave Weich of Powells.com. But reading Iweala's book was "one of those rare occasions when you see a first novel and you think: This guy is going to be very, very good."

This was not the impression Patricia Powell got when he first signed up for her Harvard creative writing class.

"He was awful," says Powell, a novelist now teaching at the University of Houston. "He wrote this stream-of-consciousness fiction, and no one in the class knew what to do with it." But what was great about him, she says, "is that he wanted to write so badly.

"He knew he had something to say, and the language was coming."

Home for Thanksgiving of junior year, right after his encounter with Keitetsi, he started writing furiously. "Just write, write, write, and this huge story came out of it," he says. He didn't have the voice right yet, but the story was good enough for him to submit when he applied, later that year, to write a "creative" senior thesis.

Kincaid read his submission and decided he had talent. They met every week. She gave him the key to her office so he could work there on weekends.

There were, to put it mildly, some ups and downs.

When he started out, Iweala says, he was trying to tell Agu's story in the third person. This turned out not to work: It was too distant, and made the violent scenes feel voyeuristic. At one point, totally frustrated, he decided to write a completely new book, from the point of view of a woman who worked with child soldiers. Kincaid steered him back to his original idea.

One day he brought her something in a first-person voice not unlike the one in the finished book. (Though the setting is not Nigeria, Agu speaks in an invented patois derived in part from the way Nigerians speak English.) Kincaid approved. She said something like "Okay, this is good, but why don't you try to revise it and fine-tune it a little bit," Iweala recalls.

Excited, he went wildly overboard. He wrote for 48 hours straight, chopping up the section he'd showed Kincaid, restructuring it, changing the cadence. His bemused roommates started filming him, "so there's this tape of me standing up talking to myself, like in a high-pitched voice, just trying to get this right." When he finished, he jumped in the shower, then dashed off to see his adviser.

Who read three pages and stopped.

"When I said revise it, I didn't mean do this to it," she said. "Go back!"

He was as dejected as he'd ever been, he says, but he'd reached a turning point. Kincaid's reaction gave him confidence in the original voice he'd tried.

He kept writing.

While he'd been struggling with the voice, he'd been doing a different kind of work, as well. He read everything he could find about children at war, reports from Human Rights Watch and Amnesty International, and books such as "First They Killed My Father," about a Cambodian child soldier. And he signed on to work with Theresa Betancourt, a Boston University researcher studying former child soldiers in Sierra Leone.

One late question had been whether to keep a death scene he feared might be too melodramatic. He was cheered when his father later told him, "Wow. You really got me there." He also worried about the ending: He wanted to show the horrors Agu had gone through, but also that not everything was lost.

Iweala finished his thesis two days early, then carried a copy with him everywhere, fearful that his residence would burn down.

He sent a copy of the manuscript to Powell. His old teacher was astonished. "It was incredible," she says. "I found it so profound, so mature. . . .

"It was as if it had been written by an old man."

This darkness is so full like it is my mother's hug. Heya! I am remembering my mother and how she is so good to me that each time she is hugging me that is all I am needing to see the dark skin of her arm holding me close to her and I am knowing that the life I am living is so good.

So what comes next if you're a 23-year-old writer whose first effort has already been called "an extraordinary book" (the Sunday Telegraph), "an astonishing debut" (Kirkus Reviews) and "a work of visceral urgency" that "heralds the arrival of a major talent" (novelist Amitav Ghosh)?

"He's so mild-mannered and soft-spoken," says Boston University's Betancourt, "that you wouldn't know the fierce passion and talent he carries around." He could, she says, "take his life in any direction he wants to."

Not long after graduation, Iweala headed for Nigeria to work with refugees displaced by Muslim-Christian conflict in the north. He can see himself doing international development work, he says. He's also applying to medical schools.

"There are a lot of directions I guess I can go in right now," he says. "I guess that's the beauty of this situation."

And yet . . .

He was writing, writing, writing, every day he was in Nigeria, trying to capture what he saw.

"Somebody would tell me something and then: 'Oh, okay, story idea,' " he says. He'd start stories but not finish them, just getting things down so he could revisit them later, write them in some other form.

"I think he has notebooks and notebooks," Kincaid says. "He writes e-mails from Africa which will take me an hour to read."

Does she think he'll keep writing, then? Medical school or no?

"Oh, if he doesn't I'll be so heartbroken," she says.

Iweala, born here to Nigerian parents, wrote "Beasts of No Nation" after meeting a Ugandan war survivor. "This huge story came out of it," he says.Iweala at his family's home in Potomac, and his first novel, "Beasts of No Nation," right.