When ABC announced that ex-supermodel Rebecca Romijn would become a series regular on ABC’s “Ugly Betty,” everyone assumed Romijn would be playing mysterious masked woman Fey Sommers. Sommers was the former editor-in-chief of Mode magazine and ex-lover of magazine founder Bradford Meade; on camera, she was seen sheathed in all those veils because of drastic plastic surgery.

But something never quite clicked with that scenario, not the least of which was that Fey would have to be significantly older than Romijn, 34. As it turns out, there was a surgery, but it was significantly more invasive than ordinary rhinoplasty.

In one of TV’s most surprising twists – and in true telenovela fashion – it turns out that Romijn is in fact playing Alexis Meade, formerly known as Alex Meade, the presumed-dead brother of Daniel (Bradford’s son). Why Alex – now Alexis – has returned to the offices of Mode midseason begs many questions. But why Alex turned himself into a woman — a very hot woman with legs for days — after allegedly dying in a ski accident begs even more questions.

“Initially, we were going to continue the [masked woman] mystery through the season,” says creator Silvio Horta, “but it was becoming too difficult to layout.”

Horta conceived the idea to bring back the Alex as a transgendered character and floated it past some people at the show. They thought he was crazy. Then he asked the network. Even with ABC riding high in the ratings, it was a shock to have the network go for it.

“We wanted to do something that was fun and jaw-dropping,” Horta says.

The Golden Globe-winner adds that the story will have emotional resonance for members of the Meade family, especially Daniel. “His father [finally] sees him as a person that could lead the company,” Horta says. “And suddenly there’s a wrench in the plan.”

Having the idea to introduce a transgender character only works if you find the right woman. In Romijn, Horta feels he has.

“I’ve wanted to work with her for a long time. Rebecca is gorgeous and she just loved the idea.”

Asked how she feels about playing prime time’s first transsexual, Romijn is confident.

“You can call her the tranny,” she says. “I’ve always known that they would take care of Alexis in the writing and be responsible about the fact that she’s a transgendered person.”

The last effort to put a transsexual on network prime-time was a sitcom developed for Fox in 2001. The show – which starred transvestite RuPaul as a nanny and was called, bad pun intended, “The Tranny” – shockingly failed to get picked up. But “Ugly Betty” is the ideal place for such a character.

“The show is campy, but there’s substance there too,” says Romijn. “The show’s about people who are real and have feelings. Betty [America Ferrera] is a character who feels differently than everyone else. This character is in that boat too.”

Accepting Romijn, once one of the world’s top supermodels, as a former man might be a hard pill to swallow for some viewers, but Romijn thinks people will buy it.

“Why not? I’m almost six feet tall. I’ve had lots of opportunities to play the pretty girl, but that’s only really interesting for about 10 minutes.”

Alexis finally revealed herself in the Jan. 18 episode, but it’s on Feb. 1 that viewers get to see the real fireworks: Alexis will confront Daniel (Eric Mabius) and begin her quest to take over Mode with the scheming Wilhelmina Slater (Vanessa Williams) at her side.

Meanwhile, man or woman, Romijn will get to wear some of the most fabulous clothes to grace prime-time TV.

“[Costume designer] Eduardo Castro is so old-school Hollywood,” she says. “He does these beautiful sketches of what every single character is wearing in every single scene. The dress I get to wear in the Feb. 1 episode is phenomenal.”

While Alexis’ shocking coming-out party will be the focus of the Feb. 1 episode, “American Idol” runner-up Katharine McPhee and “Project Runway'”s Tim Gunn also will juice up the cast. McPhee will play herself as a guest attending Mode’s Fashion Week and Gunn, “Runway'”s fashion maestro, will play a fashion reporter.

UGLY BETTY

Thursday, 8 p.m., ABC

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