Exclusive: Kit Harington prepares for action in Spooks: The Greater Good poster

Kit Harington is a busy man this spring. As well as returning to telly in season 5 of Game Of Thrones, he's also starring in Spooks: The Greater Good, the spin-off from the long-running British spy series. The TV show, which first aired in 2002, was known for it's unpredictability: basically, any of your favourite characters could've been killed at any moment.

Here's hoping the film has the same edge of danger. The plot centres on Harry Pearce (Peter Firth), the MI5 chief who's been a regular since the show's early days. In The Greater Good, a terrorist in his custody escapes, forcing Pearce to fake his own disappearance and go rogue.

That's where Harington's Will Holloway comes in. He's a former agent called in to help Pearce, and he has to weigh up whether or not to trust his former leader for, y'know, the greater good. Upping the ante from the small screen, this one's very much aiming for a movie feel with slick visuals and big explosions, and a fair amount of who-can-you-trust paranoia thrown in for good measure.

It need to aim big, as 2015 isn't short of spies in cinema, with SPECTRE and Mission: Impossible - Rogue Nation marking the return of James Bond and Ethan Hunt respectively.

Check out the exclusive poster for Spooks: The Greater Good below now:

Spooks: The Greater Good opens in the UK on 8 May 2015, with a US release date yet to be set.