It's the shocking role that's taking Cynthia Nixon from the glamour of "Sex and the City" to the grit of the "ER," and "Extra" got an exclusive behind-the-scenes look at Nixon's dramatic return to television in a role that may stun viewers.

"'ER' is a very different show than 'Sex in the City,'" Cynthia observed.

And the star gave us a sneak peek of what we can expect from her "ER" performance as a disfigured stroke victim: "I think I'm speaking to the doctors and I'm communicating, but then it dawns on me that all the things I think I'm saying, I'm only saying in my head."

But don't look for Nixon to make a return to TV as a regular just yet. For now she's enjoying just stopping by. "There's a way you get treated as a guest star that's very nice," she told us.

Plus, Cynthia admitted she still misses starring as one of those famous New York City girls: "I miss it, but not in a very immediate, pained way, just kind of a fond memory of a really wonderful time."

So could there be a reunion of the fabulous four? No word on that, but the girls are still close. "We keep in touch," Nixon said. "We email, we see each other, we talk on the phone, stuff like that."

You can see Cynthia's stunning return to television Thursday at 10 on NBC.