His debut novel, The Kite Runner, was still on its way to becoming one of the biggest selling books in recent history when Khaled Hosseini began hearing the same question again and again from fans who turned out for his readings: "When is the next book coming?"

"And there's that voice inside that says, 'Now they are going to find you out,' and there are these crises of self-doubt and you start to feel that you've said all there is to say."

Hosseini persevered, and his second novel is A Thousand Splendid Suns (Riverhead). While Hosseini, 42, published his first book in obscurity, he is now confronting the challenge of re-creating the success of his debut (which has four million copies in print). Riverhead is giving A Thousand Splendid Suns a 525,000—copy first printing.

For the new book, Hosseini has gone back to Afghanistan, this time for a powerful portrait of two women. Mariam, an illegitimate child who longs to have something of her own, is forced to accept her husband's new, younger and more beautiful wife into her household. In Hosseini's hands, the relationship between the women and their subservience to their volatile husband, set against the 30-year trauma of Afghanistan's history, makes for an emotional, often violent story.

"I worked on this book for three years and I loved these women. But there were dark days when I couldn't break through and learn what their relationship should be." The novel went through "probably the equivalent of three novels," Hosseini says, "the structure, style and voice changing each time. The more you think, the harder it gets. You have to let it come to you but then you think it will never come until a funny thing happens: you start to inhabit this other world and soon the background noise dwindles down."

Hosseini says that when he went back to Kabul in 2003, he saw women "walking down the street, wearing burqa, with five or six children, begging," and he began talking to them. "One woman told me she was the wife of a policeman who hadn't been paid in six months. The family was starving, so she sent her children out to beg. She told me another story of a widow who ground bread and laced it with rat poison and fed it to her children, then ate it herself. These stories were the germ, the starting point for the book."

The Kite Runner, Hosseini says, "was a firecracker" within the Afghani community because it talked about sensitive issues. With the new novel, Hosseini does it again. "Sex," he says, "is such a taboo subject in Afghanistan, but it's a need or a means to something, and I wanted to write about these women in the full scope of their lives, spiritual and physical. In a society where invisibility is modesty, this is scandalous." Also, Hosseini refuses to treat the burqa as a cliché for the repression of women. "For the urban women, the burqa was a disaster," he says, "but in the villages, many women wear it by choice, and this is the least of their problems, even though it's so visible to the West."

Hosseini was working as a doctor when he published The Kite Runner and the book's explosive success took him—and the rest of the world—by surprise. Now he's in a very different position, as everyone from his fans to his publisher anticipate the new book. And while he insists he's boring—"I'm not dynamic or volatile, it's all on the page"—his life is about to get interesting all over again.