In Cecily von Ziegesar's first ''Gossip Girl'' novel, back in 2002, Serena traded boarding school for ritzy Manhattan life. Now, in von Ziegesar's new version, Serena has murder on her mind

By Stephan Lee
September 30, 2011 at 04:00 AM EDT

This is kind of a genius idea.
My publisher approached me with the idea of doing a mash-up, but they weren’t sure how it would work. I’d been watching a lot of Dexter, and I wanted to figure out a way to make it funny and hilarious. I had this vision of the cover with blood all over it, and I wanted Serena and Blair to be killers. And they went for it!

We went crazy for the cover.
I think a lot of people are sort of like, ”Wait, is this real?” [Laughs]

I had that reaction too.
I’ve been telling people, ”I love this book. It’s the best thing I’ve ever written.” And they’re like, ”What is it?” ”It’s the first Gossip Girl except they kill everyone.” ”That sounds really good…I guess. Are you okay?”

What are the rules of this parallel universe? At first it looks like Serena is the only killer, then Blair gets murderous too.
Well, I’ve created this alternate universe where people are dying, and the adults are brushing it under the rug the way they used to brush under the rug partying and sex and all that.

So it’s just another vice.
Yeah! It’s an exaggerated version of what happens in the original. People are dying!

How did you come up with the death scenes?
I really didn’t have any trouble coming up with weird ways for people to die. I think I’m very twisted! I wanted to avoid guns, and I wanted to have people die in almost artistic ways, in ways that are interesting to read about.

Was there ever a point where you thought, ”Gossip Girl is my baby. Maybe I shouldn’t mess with it”?
No. Not really. If anything, I feel that by now people are like, ”Oh God, not another Gossip Girl.” You know?

Do you think you’ll continue with the mash-ups?
Not really. It’s kind of a great way to end the series, if anything.