*** (MA15+)

Director: Greg Mottola.

Cast: Simon Pegg, Nick Frost, Kristen Wiig, Jason Bateman, Seth Rogen.

IT used to be that nerds were a much maligned group that hid in the dark, stared at their computer screens and played Dungeons & Dragons.

Now they get movies made about them (The Social Network), specifically for them (Watchmen) and starring them. The latter would be Paul, written by and starring Pegg and Frost - two bona fide nerds who are happy to show off their love of all things nerdy with this sporadically funny and surprisingly sweet sci-fi road trip.

The British duo play Clive and Graeme, two Pommy geeks who make a pilgrimage to the US for the biggest nerd-fest of them all - ComicCon - and to see some of the best known sites in UFO mythology.

Along the way they meet Paul (voiced hilariously by Rogen), an alien who has been on Earth for 60 years, hanging out in Area 51, but who has recently escaped and is suddenly very keen to get home. Hot on their trail is a trio of FBI agents desperate to reclaim their foul-mouthed, pot-smoking ET.

Paul starts slowly and initially is not as funny as you'd expect from the guys who helped make Hot Fuzz and Shaun Of The Dead such cult classics, but once it builds a head of steam, the laughs start flowing and the action ramps up.

Pegg and Frost are a natural pairing and the added bonus is the always-great Wiig, again in top form, plus an against-type Bateman as a secret agent tough guy and a stellar cameo from Sigourney Weaver. But the CG extra-terrestrial Paul pretty much steals the show, and it's his absence from the first act that makes it feel comparitively slow.

Otherwise Pegg and Frost's script is pretty good, if a little rambling. Wiig's character - a devout Christian confronted by what the alien's presence does to her beliefs - is not only entertaining but one of the film's many subtly clever skewerings of American life.

Best of all for nerds like me is an aspect of the film that is soon to be a drinking game - Spot The Nerd Reference. Paul is bursting with cheeky references (some brilliant, some banal) to other films, notably the Star Wars and Star Trek series, and a large whack of Steven Spielberg's back catalogue (the legendary director even makes a quick cameo).

While not as consistently funny or sharp as their previous pairings, Paul is a heartfelt tribute to friendship, what lies beyond the stars, and being a nerd.