Lyndsy Fonseca, Nathan Fillion and Dana Delany, <EM>Desperate Housewives</EM> Lyndsy Fonseca, Nathan Fillion and Dana Delany, Desperate Housewives

A new family is moving to Wisteria Lane this fall, but not everyone's rolling out a welcome mat. Katherine Mayfair (Dana Delany) lived on the block 12 years ago with her daughter, Dylan (Lyndsy Fonseca), and aunt, Mrs. Sims (Ellen Geer), but left under mysterious circumstances. Now she's back with her teenage daughter and her second husband, Adam (Nathan Fillion), a hunky gynecologist. Ostensibly, they returned to take care of the dying Mrs. Sims, but like all new characters on Desperate Housewives, the Mayfairs harbor a dark secret that will be revealed as the season progresses. Says creator Marc Cherry: "They had to leave Chicago because something unsavory happened in Adam's professional life."

Katherine's a perfectionist and a control freak. (Think Bree, but much darker.) She's reviled by all Wisterians — particularly Bree, who by Episode 2 will go spatula to spatula with her over a lemon meringue pie recipe. "I always wanted to come up with a character everyone loves to hate," Cherry says, adding that he modeled Katherine after J.R. from Dallas and Amanda from Melrose Place. Through flashbacks, Katherine will also offer viewers a chance to look into Wisteria Lane's lurid past.

Ironically, Delany was originally offered the part of Bree, but Cherry says she turned it down three times. "I'd just done Pasadena, and it seemed too similar," Delany says. "It's very rare in life you get second chances. I'm really flattered and honored."

Also thanking the Hollywood gods is Fillion, who's still recovering from the flat tire that was Fox's Drive. "My manager asked, ‘If someone were to tell you that you could be any kind of doctor on Wisteria Lane, what kind would you be?' " he recalls. "I said I'd be a gynecologist so I could interact with all the women."

Fillion won't say whether this "interaction" will involve any illicit affairs. He will tell us that his medical expertise may play a big part in a storyline. "One might extrapolate [that] if there is an OB-GYN around, someone may have need," he says. Paging Bree's pregnant daughter Danielle?

At the bottom of the Mayfair family tree is Dylan. She's a goody-goody — cute, polite and well trained. "My mom keeps me on a rigorous schedule and a short leash," Fonseca explains. "Almost like a dog." She also suffers from a bit of memory loss. Twelve years ago, she was BFFs with Susan's daughter, Julie, until her mom decided to skip town. Now she doesn't remember a thing, leaving everyone to suspect that something horrific happened in her childhood.

She did grow up on Wisteria Lane, after all.