Jennifer Weiner could easily rest on her laurels. Her three previous novels have re-ached millions of readers in over 20 countries. Book number two, In Her Shoes, will grace thousands of multiplexes this fall and has already received advance raves. And thanks to an impressive marketing campaign mounted by her publisher, Atria, it will be difficult to avoid Weiner's presence when her next novel, Goodnight Nobody (384 pp., $26), hits stores next week.

So repeating herself was the last thing she wanted to do.

"With every book, I've always said I want to entertain my readers, give them a good time and make them think," Weiner said in a recent telephone interview. "I could write the same thing over and over again, but I've got too many stories to tell to do that."

The story told in Goodnight Nobody is a departure for a number of reasons, including the decision to swap her usual Philadelphia setting for the suburbs of Connecticut, but most of all because it's a different genre: a mystery.

"I'm a huge fan of Susan Isaacs," Weiner explained when asked why she switched gears. "I always admired how she wrote such smart, funny heroines trapped by circumstances, but who rose above them to solve crimes. They didn't have to leave the suburbs for murder and mayhem to happen. I'd love to be able to resonate with readers as much as Isaacs has."

Ensuring a coherent mystery plot — kick-started when the book's heroine, Kate Klein, stumbles across the body of her next-door neighbor — proved a challenge. "Pacing was so important, making sure all the clues were in the right place and giving the reader just enough to go on. It's tricky to strike the right balance." In order to do so, Weiner worked with an editor who "does nothing but edit mysteries."

One thing said editor changed was the murder victim's identity, which was originally slated to be Laura Lynn Baird, a strident right-wing columnist who's best described as a cross between Ann Coulter and Caitlin Flanagan. "The problem with making Laura the victim is that, as my editor pointed out, she's not exactly a sympathetic character. If you don't care who killed her, you won't exactly want to keep reading."

Ironically, Baird as supporting player is one of the most intriguing characters of Goodnight Nobody, much in part due to her inspiration. "Caitlin Flanagan was a main reason the book got written," said Weiner, specifically citing Flanagan's Atlantic Monthly tirade against mothers relying on nannies. "My daughter was 6 months old when Flanagan wrote that, and I had a nanny in 20 hours a week so I'd be able to write. I'm supposed to feel like a horrible person about this?"

Instead, Weiner poured those feelings into the creation of her heroine. A thirtysomething mother of three young children, Kate is whisked away almost overnight from her high-pressured Manhattan life to suburban Connecticut motherhood, where she's the odd woman out amidst a sea of Stepford-esque stay-at-home mothers. Unlike them, Kate is still grasping the nuances of motherhood, wondering why what seems automatic to everyone else still eludes her.

"I wanted to capture a sense of how women deal with the internalized pressure of motherhood," said Weiner. "Here are these high achievers, high-performing women who are suddenly raising kids and, even though it's the 'best job ever,' feel like they failed to raise them right. So many mothers, and great ones, spend their time living inside their heads, thinking about what's wrong with them."

These pressures, she explained, have changed considerably from her childhood years. "When my brothers and sisters and I were growing up, my mom had a playpen full of toys she stuck us into — which you just can't do anymore. You can't just leave the kid in there and go watch TV or do your thing. But every time I tried to explain this to her, she wouldn't get it. The standards are so different now."

While Goodnight Nobody is still fresh in Weiner's mind (she only finished the copy edits at the end of July) she's eagerly anticipating her next project. "I'm interested in exploring a friendship between two very different women. One's more of an observer, in the sidelines, while the other's far more outgoing, but they end up friends anyway. Until it all goes horribly wrong." The premise's resemblance to Zoe Heller's What Was She Thinking? is no accident. "I loved that book, as well as the anthology The Friend Who Got Away, which was out a few months ago. It's such a great topic to deal with."

For now, she's focusing on her next book tour — which includes a stop in her old Connecticut stomping grounds. "I had to fictionalize it," Weiner said, laughing, "because otherwise I'd be facing a horde of angry moms in Merion with flaming sticks!"

Jennifer Weiner appears Sat., Sept 24; 11 a.m., Costco, 201 Allendale Rd., King of Prussia, 610-337-6601; 1 p.m., Wal-Mart, 1 Franklin Mills Blvd., 215-281-3159; 7 p.m., Borders, 1 S. Broad St., 215-568-7400.