'Gossip Girl' EP: Katie Cassidy is not Gossip Girl, will fall for Nate

We've heard all about the fabulous time that the "Gossip Girl" cast had while shooting the Sept. 13 Season 4 premiere in Paris, but back on the Upper East Side, trouble was brewing. Nate (Chace Crawford) has spent his summer sinking to new lows courtesy of Chuck's little black book, but when he meets Katie Cassidy, he's inspired to clean up his act.

"This is definitely a big story for us," says executive producer Stephanie Savage. "Katie's with us for a good long time -- at least for the first half of the season."

Of course, the "Melrose Place" star isn't what she seems. If there's anything we've learned from "Gossip Girl" over the years, it's that no newcomers arrive in town without some skeletons in their always-fashionable closets. Cassidy's character Juliette is no exception to the rule.

"By the time the mystery is over, you'll know everything there is to know about Juliette," Savage teases. "Her entire back story will be revealed."

After watching the first two episodes of the season, we thought that Cassidy would make an excellent Gossip Girl. She's definitely got her eye on all of our Upper East Siders, and nothing slips by her. Not so fast, Savage tells us. "We're not going to find out who Gossip Girl is this season," she says definitively.

As for Juliette's romance with Nate, Savage says, "The relationship definitely starts off as something with an agenda behind it, but by the end, it's real for both of them." She laughs. "Isn't that always how it happens? You start a relationship trying to use somebody and you fall for them every time."

We can't wait to see Juliette tangle with Blair (Leighton Meester) and Serena (Blake Lively), but B and S may have their hands full at the moment as their stories unfold on the Columbia campus.

"It's a really fun story that our audience will really like," says Savage. "The center of our show is back in the right place, Uptown. It's a collegiate, classically preppy environment that's just perfect for our characters."

Follow Zap2it and @cadlymack on Twitter and Zap2it on Facebook for the latest TV, movie and celebrity news.

Photos: CW