The Warriors cat-centric fantasy series by Erin Hunter (HarperCollins) has quietly crept onto bestseller lists via grassroots fan support on the Internet. But the era of stealth-like sales may be gone, as these days the arrival of a new Warriors book makes a bit of a roar. The most recent release: Warriors: The New Prophecy: Starlight (April) leapt out of the gate with a 100,000 copy first printing. Numbers like that have helped make Warriors the cat's meow for booksellers as well as feline and fantasy fanciers.

The books, written for middle graders, feature four clans of feral cats that must fight for survival in a dangerous forest; the novels have been praised by critics as action-packed, suspenseful and intriguing. For many, maps and charts of clan territories and allegiances, as well as fanciful character names like Bluestar and Bramblepaw, add to the charm. The Warriors are the joint creation of British children's authors Kate Cary and Cherith Baldry, who generate the stories together and then alternate writing the novels under the pseudonym Erin Hunter.

Into the Wild, the debut Warriors title, was published in January 2003 with little fanfare. But the title quickly caught on with young readers who wanted to spread the word about it online, in chat rooms and on fan sites. Those early Warriors enthusiasts soon had more to chat about, too, when the second book in the series, Fire and Ice, arrived on bookshelves in May 2003.

The cats' adventures continued through six Warriors titles, wrapping up in late 2004. But thanks to the release of paperback reprints of the original six titles, and the launch of a follow-up series, Warriors: The New Prophecy, in early 2005 (again with a new book arriving approximately every four months), readers didn't have long to wait for their next feline fix.

To date, the Warriors books (the six originals and four of a planned six New Prophecy titles) have more than 1.5 million copies in print in their combined formats. And the swell of support online has resulted in more than 200 fan Web sites. Sounds like purrfectly pleasant progress.