Stephanie McAfee’s Diary of a Mad Fat Girl (NAL, $15) offers a fascinating tale, but not between its covers. The girl-buddy cape, starring a sassy, overweight Mississippi teacher, brims with local color but is burdened by too much plot and too little nuance. With an endearingly flawed narrator in a conflicted relationship, this is chick-lit territory that many talented writers — Jennifer Weiner and Rebecca Wells among them — have explored far more deftly.

What makes “Diary of a Mad Fat Girl” so fascinating is how it became a book in the first place. McAfee is a former teacher from Mississippi who, after being rejected by numerous literary agents, decided to self-publish her e-book in December 2010. “When I discovered Smashwords (and later Amazon KDP and Barnes & Noble PubIt!), I thought, ‘Hey, why not give this a try?’ ” she says in the book’s publicity materials. “Kindle ads were on the back of literally every magazine we subscribed to at the time. . . . And what does everyone want after Christmas? A bargain. Enter my 0.99 cent ebook.”

At the time, McAfee did not own an e-reader. But she spread the word about her first novel to her 400 or so Facebook friends and watched as her book became an underground hit.

The e-book sold 145,325 copies from January to August 2011, McAfee says, and spent 12 weeks on the extended New York Times e-book fiction bestseller list and two weeks on the combined e-book and print-fiction list. Agents started calling, and NAL offered McAfee a three-book deal for an undisclosed amount. Sales from the e-book, she said, were “a bit more” than her annual teaching salary; she’s now writing full time. “I know how it feels to hit the jackpot,” she says.

E-book software and social networking have helped make self-publishing and self-promotion simple and inexpensive, and e-book bestseller lists have given the form cachet. John Locke, author of the best-selling novel “Saving Rachel,” boasts that sales of his e-books rank among those of Stieg Larsson and James Patterson. Last year, he became the first self-published writer to sell 1 million books on Kindle; he has since signed a sales and distribution deal with Simon & Schuster. Young-adult fantasy-lit sensation Amanda Hocking sold more than 1 million copies of her self-published e-book series and last year made a $2 million deal with St. Martin’s.

“Diary of a Mad Fat Girl” by Stephanie McAfee was originally a 99-cent e-book. (New American Library)

A book placed with a traditional publisher is edited, made into a physical product, marketed and shipped — expenses that are built into the retail price. Self-published e-books, though, often sell for less than $3. McAfee’s 99-cent e-book, substantially expanded by the author, and edited and marketed by NAL, will cost $15 in paperback. Hocking’s “Switched” was 99 cents as an e-book but is an $8.99 paperback. Locke says he plans to raise the prices of the existing novels from his popular Donovan Creed series “to prevent self-competition with the paperbacks.” (For $9.99, you can buy the paperback edition of his book “How I Sold 1 Million ebooks in 5 Months.”)

Does a higher price beget the expectation of higher quality? (As one Amazon reviewer said of McAfee’s e-book: “You bought a book for 99 cents and you expect Jane Austen?” ) No matter the price or format, McAfee’s novel is not Austen. But it’s charming, light entertainment with a back story that’s an inspiring personal tale and a lesson in publishing’s changing landscape.

From our previous reviews

The three daughters of a Midwestern Shakespeare professor are summoned home to tend to their ailing mother in Eleanor Brown’s The Weird Sisters (Berkley, $15), “a charming novel about star-crossed siblings who just so happen to know the greatest English verse much better than they know themselves,” wrote Ron Charles.

New York chef Gabrielle Hamilton’s memoir Blood, Bones and Butter (Random House, $16) — a fascinating look behind the restaurant scene as well as an affecting coming-of-age tale — is by turns gritty and poetic, wrote Joe Yonan.

Play Their Hearts Out (Ballantine, $16), “a tour de force of reporting” by George Dohrmann, takes readers inside the hypercompetitive world of youth basketball, telling the story of a promising player and the coach who hoped to make him a star, according to Sean Callahan.

Drawing on an episode from the 1940s when researchers “fed radioactive drinks to unsuspecting pregnant women as part of a nutrition study,” Elizabeth Stuckey-French’s The Revenge of the Radioactive Lady (Anchor, $15) tells the fictional story of one such patient who, at 77, takes revenge by insinuating herself into her former doctor’s family. Adam Langer called the novel “an ambitious, dark, contemporary American comedy.”

Poser (Picador, $15), Claire Dederer’s memoir about yoga and modern parenting, is fueled by a “wry ambivalence about motherhood that smuggles her book out of the New Age ghetto,” according to Justin Moyer.

Perilous Fight (Vintage, $17.95), Stephen Budiansky’s “rousing story of the naval war of 1812,” is a vivid account of how America fought for respect from its former Colonial masters, according to Evan Thomas.

Krug writes the New in Paperback column for The Post every month.