Gossip Girl heroines Blair Waldorf and Serena van der Woodsen become trendsetting serial killers in Gossip Girl, Psycho Killer, Cecily von Ziegesar’s tongue-in-cheek reimagining of her 2002 novel that launched the bestselling series. Little, Brown’s Poppy imprint, which has sold more than six million copies of its 13 Gossip Girl novels, will publish the new novel in October with an announced 100,000-copy first printing. Though not a conventional mashup in the vein of Pride and Prejudice and Zombies or Little Women and Werewolves, since von Ziegesar gives the new twist to her own novel, the book grew out of the publisher’s interest in exploring the mashup genre.

Cindy Eagan, Poppy’s executive editorial director, explains that she and Andrew Smith, v-p and deputy publisher of Little, Brown Books for Young Readers, had been talking for quite a while about doing “some kind of mashup of Gossip Girl. We thought it would be the quintessential mashup for Poppy to publish. But we didn’t want to do a zombies, werewolves, or vampires angle. We wanted to do something that hadn’t been done before—something over the top.”

While deliberating a theme for a Gossip Girl mashup, Eagan recalled reading Bret Easton Ellis’s American Psycho when it was first published in 1991. “I remember being addicted to the book—and also freaked out and repulsed by it at the same time,” she says. “It’s a satirization of the American dream that is totally twisted. Similarly, in Gossip Girl, Psycho Killer, these are beautiful, rich girls who supposedly have everything—but they go crazy, and, sardonically, killing becomes a competition between them. Cecily has taken a lot of the themes she explored in Gossip Girl and turned them on their side here, using her brilliant sense of humor.”

Von Ziegesar, who immediately loved the new concept, believes it’s a good fit for Gossip Girl. “I have a sort of evil sense of humor,” she notes, “and I thought this would be a perfect opportunity to do a dark comedy—darker than the comedy that is already in Gossip Girl novels.”

This was confirmed when she reread her original novel. “It occurred to me that there are so many opportunities in that novel to have people die, because everyone is mad at everyone else,” she says. “It was a matter of taking it one step further. It’s not meant to be taken seriously—it’s like the bitches are back and now they have knives! Instead of brushing their kids’ bad behavior under the rug, the adults are now brushing murders under the rug.”

Von Ziegesar notes that Gossip Girl, Psycho Killer, like other mashups, uses text from the original book, but it expands that story line. “New characters are brought in for the sake of dying,” she quips. “I did want this novel to be original, though it’s funny in that the first novel was very loosely based on The Age of Innocence, so in a way this is a mashup of a mashup.”

Is the author worried that the new novel’s grisly premise will alienate hardcore Gossip Girl fans? “Oh, everyone likes a good serial killer book or movie!” she responds. “It’s all in the execution—no pun intended. So if I can pull this off, keep it high comedy and keep readers laughing and still stay true to the characters, that will be great.”

Gossip Girl, Psycho Killer by Cecily von Ziegesar. Little, Brown/Poppy, $10.99 paper Oct. ISBN 978-0-316-185097-0