Kit Harington has teased that fans of Spooks will not be disappointed with the upcoming film adaptation.
The Pompeii and Game Of Thrones star is set to play Sir Harry Pearce's (Peter Firth) protege Will Crombie in Spooks: The Greater Good, which started shooting in March.
"It's great. It's a really brilliant script, it's fascinating, it's very fast-paced. It follows in the vein of the TV show but it's got a bigger budget," he said.
The 27-year-old, who is best known for playing Game Of Thrones' Jon Snow and slave-turned-warrior Milo in Paul WS Anderson's Pompeii, is excited about swapping swords for spy gadgets.
"I find it very, very exciting. I get to do action but in a different genre, which is fun," he added.
Peter will reprise his role as Harry, the head of counter-terrorism department at MI5, in the film, a role he played for all 10 series of the BBC spy drama until the show ended in 2011. Jennifer Ehle, Tuppence Middleton and Elyes Gabel also have roles.
"We've got Peter Firth coming back, who is such a staple within Spooks," Kit continued, adding: " Jennifer Ehle is now in it, and a wonderful young actress called Tuppence Middleton has just joined the cast."
Jonathan Brackley and Sam Vincent, who took over as head writers for the last two years of the Spooks TV series, have written the script for the film, which is being directed by Bharat Nalluri, who previously directed the first episodes of the programme.
Spooks: The Greater Good is expected to be released in 2015.