Doctor Who will appear as a 3D television movie to mark the 50th anniversary of the sci-fiction show.

BBC insiders said TV writer and producer Steven Moffat was granted "free reign" to come up with scripts for the special episode, which could end up being up to 90 minutes long. The film-style episode will also be shown 3D in theaters around the world at the same time as it is screened by BBC1.

Referring to the anniversary episode, which began filming in March, lead actor Matt Smith said: "I read the script and clapped at the end." He added, "It's epic and vast and fans won't be disappointed. It's the biggest and best exciting year and this script delivers on all those things."

The new series premieres on March 30. Executives behind Who confirmed the titles of and released posters for the first four episodes early in March. Plot details have also been posted on the BBC America website.

The Doctor's latest adventures begin by him searching for his companion Clara Oswald - "an Impossible Girl" he has already lost twice, according to the network. Together they find battle monsters on distant alien planets and find themselves trapped in a Russian submarine with a deadly passenger. Viewers also see them chasing ghosts, "facing the Crimson Horror in Victorian Yorkshire," and having to go head-to-head an army of upgraded Cybermen, among other adventures. Among all the action the Doctor's "oldest secret threatens to be revealed" as the world's longest running science fiction series gets closer to its 50th anniversary in November 2013.

Following the premiere of Doctor Who on March 30, Matt Smith was a guest on BBC America's he Nerdist at 10:00 p.m. ET/PT.

Clara Oswald is played by Jenna-Louise Coleman (Captain America: The First Avenger). Moffat revealed that the series will see "plenty of new monsters" and he added, "watch out for the Spoonheads, the Whispermen, and - my favorite - the Vigil."

Tags: Doctor Who