Alexander McCall Smith has a laugh that could charm a hissing cobra, and he's about to let loose with one now.

Slumped diagonally across a stiff hotel armchair, the Scottish author of the six wildly successful novels in the "No. 1 Ladies' Detective Agency" series -- and of much, much more, but we'll get to that -- is expanding on a story about a psychiatrist who said he'd been prescribing the books to depressed patients, with good results.

"I don't know whether they got that plus Prozac," McCall Smith says, starting to grin. Then: "You can imagine the control group. One group would get the book and the other one would get blank pages. The placebo reading group!"

The laugh that follows sends his voice up nearly an octave. His whole body shakes, rumpling his coat and skewing his tie. It's not the greatest joke you've ever heard, perhaps, but McCall Smith's good humor is irresistible -- and surely a factor in his books' success.

The rest of the formula is something of a mystery, though. Indeed, the question that prompted the psychiatrist story is one that seems almost rude to ask:

How is it that these quirky, slow-paced, mild-mannered entertainments -- which are not really detective stories, despite the series title -- have acquired millions of readers around the world?

They're set in Botswana. (Quick: find it on the map.) Their heroine, Precious Ramotswe, is a woman of "traditional build" (she's fat) who shuns violence, lacks interest in sex and appears to spend as much time sipping bush tea as she does solving clients' problems. Not the normal ingredients to send books flying off airport racks.

In the conversation that follows, a variety of possible reasons for the success of "The No. 1 Ladies' Detective Agency" will emerge. But McCall Smith, once his laughter subsides, quickly tosses out a central one.

The books are "portrayals of people in whom generosity of spirit is very strong," he says.

"So there's a bit of novelty in that."

We don't forget, thought Mma Ramotswe. Our heads may be small, but they are as full of memories as the sky may sometimes be full of swarming bees, thousands and thousands of memories, of smells, of places, of little things that happened to us and which come back, unexpectedly, to remind us who we are.

-- "The No. 1 Ladies' Detective Agency"

There's more than a bit of novelty in McCall Smith's writing career. For one thing, he's only recently started doing it full time.

His primary career, put on hold three years ago, was as professor of medical law at the University of Edinburgh. He's been vice chairman of the Human Genetics Commission of the United Kingdom and a member of the International Bioethics Commission of UNESCO. All this didn't leave much time for creative writing -- not to mention his role as co-founder of an amateur musical ensemble called the Really Terrible Orchestra, in which he plays the bassoon.

"The thing that I love," says his American editor, Edward Kastenmeier of Pantheon, "is that he wrote 'The No. 1 Ladies' Detective Agency' " -- meaning the first three books of the series, before it became a hit -- "on vacation!"

He could do this because he lacks the agonizing gene with which most writers are born.

McCall Smith writes as much as 4,000 words a day, typically without significant revisions. "Writing fiction, I really just sit there and it just comes," he says, and you can almost hear a chorus of envious agonizers grinding their teeth. Right now, the man has three sets of novels in print besides "No. 1 Ladies."

There's "The Sunday Philosophy Club," another series of not-really-detective fiction whose second volume, "Friends, Lovers, Chocolate," hit some bestseller lists this fall. Isabel Dalhousie, its Edinburgh-dwelling protagonist, edits a journal of applied ethics and finds moral dilemmas proliferating in her daily life -- along with the odd mystery to solve.

There's his series of academic satires, "Portuguese Irregular Verbs," among them the evocatively titled "At the Villa of Reduced Circumstances."

And there's McCall Smith's current favorite, "44 Scotland Street." Inspired by Armistead Maupin's "Tales of the City," which began as serial fiction in the San Francisco Chronicle, the books in this series appear first in daily, thousand-word chunks published by the author's hometown paper, the Scotsman.

McCall Smith's combined U.S. sales over three years are approaching 6 million books. Millions more have been sold overseas. Even "44 Scotland," which he thought "very Scottish and local," is getting translated: "We just sold Lithuanian rights and Polish rights."

Still, Precious Ramotswe is by far his best-known creation. More commonly called Mma Ramotswe -- the "Mma" is an honorific, like "Madam" -- she entered his mind as what he calls a "germinal image" 25 years ago.

McCall Smith -- who's "Sandy" to his friends -- was born in 1948. He grew up in what is now Zimbabwe but was then the British colony of Rhodesia, where his father was a public prosecutor. At 18, he moved to Scotland to continue his education. A dozen years after settling in Edinburgh, he returned to Africa by means of a temporary teaching job in Swaziland.

It was then that he got to know and love nearby Botswana, through visits to a childhood friend living there. One day, he and his friend's wife bought a chicken from a cheerful woman who chased it down for them, snapped its neck, presented it "with a flourish" -- and somehow caught the writer's fancy.

"I just remember thinking: What is this woman's story?" he says. "She had a beautiful yard, she had this nice smile, and I thought: There's a story there, in this apparently rather straightforward life."

Nothing came of it for a long time.

Back in Scotland, McCall Smith built his academic career, got married -- his wife, Elizabeth, is a doctor -- and helped raise two daughters. After some less than scintillating youthful stabs at adult fiction, he started writing successful children's books in his spare time. But he never lost his fascination with Botswana, periodically returning to work on legal projects at the university there.

Finally, in the late 1990s, he started writing about that woman with the apparently straightforward life.

He gave her intelligence, intuition and a calm temperament. He gave her a father who loved her and left her his cattle, which she sold to buy a house and start a detective agency. He gave her a tiny white van to drive; an assistant who scored 97 percent on her examinations at the Botswana College of Secretarial and Office Skills; a shy suitor named Mr. J.L.B. Matekoni, proprietor of Tlokweng Road Speedy Motors; and a stream of clients with concerns about things like unfaithful husbands and independent-minded teenage daughters.

He took the finished manuscript to the Edinburgh-based Canongate Books, which had recently put out a volume of his short stories -- and got turned down.

"I felt the need for there to be more grit in the book," says Canongate chief Jamie Byng, sounding remarkably calm for a man whose decision cost his company millions.

Before McCall Smith and Canongate parted ways, Mma Ramotswe's creator did make her story somewhat edgier. Among other things, he gave her a bad early marriage, to a charismatic jazz trumpeter who beat and then abandoned her. He has no regrets about this, he says. But he still had to find a new publisher.

In a fairy tale version of this story, that new publisher -- Edinburgh's Polygon -- would have found itself with an immediate smash on its hands. In actual fact, the first print run was 1,500 copies and when McCall Smith was told there'd be a second, he thought: "Well, gosh, that's a runaway success." It wasn't until "The No. 1 Ladies' Detective Agency" series was picked up in the United States, by Pantheon, that it really began to take off.

Which brings up that rude question again:


Mma Ramotswe did not want Africa to change. She did not want her people to become like everybody else, soulless, selfish, forgetful of what it means to be an African, or, worse still, ashamed of Africa.

-- "The No. 1 Ladies' Detective Agency"

Start with the feel-good factor -- and the timing.

"These books are comfort food," says Kastenmeier, who nailed down the American rights in early 2002. "And in the year after September 11, I think Americans were interested in reading books of that nature."

Throw in McCall Smith's "generosity of spirit" idea as a variation on this theme.

"People are so accustomed to the contemporary novel being reflective of social pathology and dysfunction," he says. Small wonder they sit up and take notice when they encounter one "in which human nature is portrayed as being potentially rather better."

Add the uniqueness of the protagonist.

"To me, these books -- they're about Mma Ramotswe," Kastenmeier says. They're about "this great-hearted woman" whom readers come to love. It helps that her appeal seems inimitable: "When a book is very successful, as an editor, you tend to see a lot of knockoffs." This hasn't happened, at least so far.

Factor in McCall Smith's easy assumption of the female point of view.

Earlier this year, Janet Malcolm began a lengthy ode to "No. 1 Ladies" in the New York Times Book Review with this point. Among the series's "many oddities," she wrote, "is its unabashed sexism. McCall Smith treats the weaker sex -- men -- with pitying condescension."

Malcolm also pointed out that while Mma Ramotswe has been called "The Miss Marple of Botswana," the Agatha Christie comparison is false -- McCall Smith's heroine being sui generis. She went on to laud his writing for its "playfulness" and "double-edged irony."

And yet: All these explanations, even combined, don't seem quite enough.

McCall Smith readily agrees, for instance, that it would have been much harder for the "Sunday Philosophy Club" series to break through to a mass audience if it had been published before "No. 1 Ladies." But why is this? Isabel Dalhousie may not be quite as distinctive a creation as Mma Ramotswe -- though how many trained philosophers do you know who go around butting into strangers' lives after deciding there is a moral imperative for them to do so? -- but the comfort food analogy, playful writing, underlying sympathy for women and fundamental generosity of spirit apply to her fictional world as well.

No. The key difference, McCall Smith believes, lies in the continents on which the books are set. "The Botswana books are really about Botswana, and about Africa," he says. "And about, I suppose, some of the characteristics of people who live in Africa."

"Some" is a key word here. McCall Smith has deliberately steered a course between two common types of writing about Africa by outsiders: what he calls the "post-colonial romp," which romanticizes the continent, and the "heart of darkness novel," with its bleak vision of corruption, economic failure, genocide and disease.

He has no quarrel with those who deal with the negatives, he says: "Writers obviously have to bear witness to the harsh face of the age." But he's chosen to home in on aspects of Africa he thinks help balance the picture. Many people in countries such as Botswana are "remarkably generous in their view of things," he explains, and visitors are often overwhelmed by their kindness. But kindness and generosity "don't get air time."

McCall Smith has taken some heat for his decision to downplay AIDS, which has devastated southern Africa. He says he was once told that "writing about Botswana and not confronting AIDS is like writing about the Blitz in London without any bombs going off." He's got his reasons, though.

"If you talk to people, they're all frightened, they are so distressed by this," he says. "Everybody has lost a close friend or family member." But if he made the pandemic more prominent, "the books would become tragedies," which he "very specifically" does not want them to be. That would defeat an important part of their purpose, which is "getting people to engage with Africa at a human level."

"People who read these books may never have thought of Africa," he says, or may see Africans as not human, as the "other."

McCall Smith sends money to Botswana for AIDS relief, through a private fund he set up but prefers not to discuss in detail. And he has put AIDS in his books, though without naming it. At one point, a major character's brother falls sick. At another, he has an Anglican cleric, the Rev. Trevor Mwamba -- a real person and friend of the author's, as it happens -- delivering a sermon about "this cruel illness that stalks Africa."

All of us can help, Mwamba says: "We can do that by acts of kindness to others; we can do that by relieving their pain."

Talking about AIDS has changed McCall Smith's demeanor entirely. His voice is quiet now, and he leans forward intently, elbows on knees.

The question before her now was that utterly trite one, which must have graced the columns of countless problem pages: "My best friend's boyfriend is cheating on her. I know this, but she does not. Should I tell her?"

It may have been a familiar problem, but the answer was far from clear.

-- "The Sunday Philosophy Club"

He is not, however, a man inclined to stay somber long.

"I'm interested in applied ethics," he says at one point, explaining Isabel Dalhousie's preoccupation with the ethical quandaries of everyday life, and he goes on to discuss his own fascination with issues of forgiveness. Then he mentions the International Forgiveness Institute of Madison, Wis.

"Imagine the infighting," he says.

And laughs.

He gets unsolicited advice about Isabel's sex life. It would be empowering, women tell him, if the heroine of "The Sunday Philosophy Club" had an affair with her much younger friend Jamie. But fans would be well advised not to hold their breath.

"Erotic tension is much sexier than fulfillment," McCall Smith says. Plus, he thinks his readers like seeing other people not getting what they want:

"It's the story of all our lives."

Another laugh.

Ask him about the roots of his creative drive and he mostly ducks the question. "I think a lot of writing is a response to some personal sense of loss and separation," he says, but he doesn't want to go farther than that. "I think if one were to go into those issues too much, one might actually end up being resolved and stop writing."

Hmm. Many of his female characters, it is suggested -- Mma Ramotswe and Isabel Dalhousie among them -- have been abandoned by self-absorbed men: Could this have to do with his grandfather the doctor, who left a wife and four children and ran off to New Zealand with a patient in 1914?

"I've never been abandoned," he says, and if he has hidden fears, "I'm not conscious of that." But he's too polite to reject the idea out of hand. And there is one thing, he volunteers, that he is aware of doing when he creates his characters:

He writes their mothers out of the stories.

"They're all out. Mma Ramotswe's mother was written out by a train," he says. "I wrote mothers out of all my children's books as well." As for young Bertie in "44 Scotland Street" -- whose hilariously pushy female parent insists that her saxophone-playing 5-year-old speak Italian -- "he wants to write his mother out of his life."

Big laugh.

"I suppose my mother was quite dominant," McCall Smith says a minute later. It may also be worth noting that she, too, wrote a book set in Africa -- which was never published.

Best not to go there. That might be pushing analysis too far.

Whatever the underlying motivation, McCall Smith remains joyfully unblocked. He's committed to three books a year now, in three different series. He's finished "Blue Shoes and Happiness," the seventh volume in the "No. 1 Ladies" series, which will be published here in April. He's working on a third "Sunday Philosophy Club" book. As for "44 Scotland Street," the second volume, "Espresso Tales," is just out in the United Kingdom, and he's hard at work on the third, still writing his daily episodes for the Scotsman.

He's what? Surely he gives it a rest on book tours!

But no.

"I wrote one on the plane coming in," he says. "Tomorrow, I'll have two hours on the train."

"People who read these books may never have thought of Africa," says the "No. 1 Ladies' Detective Agency" author. Alexander McCall Smith modeled his "No. 1 Ladies" heroine after a woman who sold him a chicken: "I just remember thinking: What is this woman's story? She had a beautiful yard, she had this nice smile, and I thought: There's a story there, in this apparently rather straightforward life."