Khaled Hosseini’s novels about Afghanistan and its people can break your heart. But readers are not the only ones who find themselves deeply moved by the darker elements of his stories.

“I haven’t written anything that introduced an emotion in a reader I haven’t experienced tenfold already,” says Hosseini, the bestselling author of The Kite Runner, A Thousand Splendid Suns and now And the Mountains Echoed.

“I don’t know how long it took you to read the books, a week or two, but I live with these people for years, and they’re very real to me. They’re like kids. I’m there when they’re conceived. I see them come into focus. I hear their voices. I think about them all day. … It’s not like I know what’s going to happen. Writing is a process of discovery. I never outline, so I never know how these characters are going to fare. It’s intensely emotional for me.”

And the Mountains Echoed (Riverhead, $28.95) could make anyone emotional. In it, Hosseini — who appears Wednesday at Temple Judea in Coral Gables for Books & Books — tells the story of a devoted young brother and sister separated when their desperate father sells his daughter to a wealthy couple who can’t have children. The novel sweeps across decades, from the Afghan countryside to bomb-torn Kabul, to Paris, California and Greece, as the repercussions of this terrible act resound through many lives.

But is this act so heinous? Structurally more complex than Hosseini’s earlier books, And the Mountains Echoed suggests there are reasons for the unfathomable choice the father makes, just as our own decisions often surface from murky waters. The book shares little of The Kite Runner’s moral simplicity, instead delving into thornier ground from several points of view.

“In this book you see their motivations come from more complicated places,” Hosseini says of his characters, who also include an ambitious but weak-willed Afghan-American doctor and an alcoholic, expatriate Afghan poet who finds motherhood unfulfilling. “When I was writing this book I saw as the characters were taking shape more questions than answers kept arising about who they really were. There weren’t reductive questions about good and bad that could be answered. Everyone felt fallible. It’s so much closer to how we live our lives.”

Like those of his characters, Hosseini’s life must feel a bit chaotic at times; he’s not exactly resting on his success. More than 38 million copies of his novels have been sold worldwide, 10 million of them in the United States. The media blitz for And the Mountains Echoed — No. 2 on The New York Times bestseller list at the moment — is in full swing.

The author, 48, who came to the United States with his family from Afghanistan when he was 15 and now lives in Northern California with his wife and two children, is also a Goodwill Envoy for the United Nations refugee agency, and founder of The Khaled Hosseini Foundation, a nonprofit that offers humanitarian aid to people in Afghanistan (you can read about it at khaledhosseinifoundation.org).

In his books, Hosseini chronicles the traumas Afghanistan has endured, including invasion by foreign powers, the rise of the Taliban and the rule of drug- and warlords. His strong ties to his homeland also inform his characters, from the boys with an unbreakable bond in The Kite Runner to the brave, embattled women of A Thousand Splendid Sons to the large cast of And the Mountains Echoed.

“Khaled Hosseini is special because he seems to move effortlessly and subtly between cultures,” says Diana Abu-Jaber, author of Birds of Paradise, Crescent and The Language of Baklava. “His new book really showcases his masterful storytelling — the characters are modern, but the sensibility seems ancient and mythological.”

Indeed, And the Mountains Echoed opens with a fairytale about a stolen child, one that comes true in an unexpected way.

As closely identified as he is with Afghanistan, Hosseini says he is open to other inspiration.

“You don’t want to just become someone for whom there are a set of expectations for these kinds of stories and these kinds of characters,” he says. “That is not something I’m interested in doing. If it was a story that compelled me and caught my fancy the way these books had, then I would pursue it if I felt compelled.”

The compulsion to tell stories banishes some anxieties, he says, but breeds others.

“Once I’m in the thick of writing, it becomes all I can think about,” he says. “I’m so into solving the mystery, I’m in this mental bunker, and all that stuff recedes in the background. The angst I do feel is feeling like I have nothing left to say, that fear you’re going to run out of things to say or start repeating yourself. There is no guarantee just because you’re writing that anything worth writing is coming out.”