The first official photo from NBC's upcoming telecast of "Peter Pan Live!" has been released Wednesday, Sept. 3, and it shows Allison Williams in full costume as the boy who never grows up.

The 26-year-old actress and classically trained singer, who stars as Marnie Michaels in the HBO comedy-drama series "Girls," posted the photo on Instagram, giving her fans a sneak peek at what she is going to look like during the live production.

"The transformation begins! My first shoot as Pan," Williams captioned the photo, in which she is seen rocking a short hairdo.

"Fun fact: I was all ready to cut my hair, then was told by the folks who actually know what they're doing that a wig works better for everybody," she added in her post in the image sharing site.

During her appearance on "Today" Wednesday, Williams talked more about her role in the holiday special. "It's an absolute dream come true; the whole process just as it (is) sort of starting to get going is so fun; already I can only imagine what the next couple of weeks and months are going to bring," she said according to AceShowbiz.

"We're so excited about the live part of it," added, Williams, who is the daughter of NBC News anchor Brian Williams. "I think that's what makes it so fun. That's what makes it exciting that it's theater, but it's right in the comfort of your own home. That's what attracted me to it."

"I have wanted to play Peter Pan since I was about three years old, so this is a dream come true," said Williams in a July statement posted on Aint It Cool. "It's such an honor to be a part of this adventure, and I'm very excited to get to work with this extraordinarily talented team. And besides, what could go wrong in a live televised production with simultaneous flying, sword fighting and singing?"

"Peter Pan Live!" will air on Dec. 4 on NBC. Christopher Walken plays Captain Hook, while former "Smash" star Christian Borle plays double roles: Captain Hook's right-hand man Smee and Mr. Darling.