Homage to zombie films? Check. Cop flicks? Check. Aliens?...With the kind of silly success that Simon Pegg and Nick Frost have achieved from their two previous cinematic outings together (Shaun of the Dead and Hot Fuzz), a film about aliens seemed a natural next step for the pair. And although their favoured director Edgar Wright sat this one out, Greg Mottola (Superbad, Adventureland) looked to be more than a competent substitute. Somewhere along the line however, something didn’t quite click.

If you’re a self-confessed comic geek, then there’s only one place in the world to make a pilgrimage to and that’s Comic-Con in the US of A. But Graeme (Pegg) and Clive (Frost) don’t just adore all things comic-y, they’re also huge fans of sci-fi and alien-centric material. That’s why after the convention, they head off in their RV on a tour of some of the most famous alien hotspots.

Along the way, out on an empty road in the middle of the desert, they suddenly get involved in an accident, which leads them to discover Paul: a full-on alien (voiced by Seth Grogen). After he explains his predicament to them, they set off on a manic road trip in a bid to get Paul back home. But it soon transpires that Paul’s absence is noticed, and the guys who had him before he escaped, want him back.

But Paul has other ideas; he’s been here long enough now, and realises that there really is no place like home. With a bunch of suited types breathing down their necks, the chase is definitely on.

Much like their other films, Paul's premise is a simple one. Where this one does differ however is in its execution. Whereas the previous films sparkled with originality, there’s something just a little too obvious about this one. Right from the off, it’s clear where the story is heading, and whereas their previous little deviations off the path have been little gems, here they feel clunky and awkward.

One of the problems is the love interest. Kristen Wiig’s character Ruth isn’t only not essential, her back story doesn’t provide anything of interest. On paper she goes through a transformation; that of a super religious freak with the use of one eye, into an all-seeing foul-mouthed freak. It’s hardly ugly duckling to beautiful swan stuff. The laughs are supposed to come from her forming own ‘whacky’ expletives, but they all end up falling flat. Quite frankly, it’s embarrassing.

And then there’s Paul himself. It’s understandable that his physical form should take that of our classic interpretation of the little green alien; the type that was developed during the forties and fifties and adorned film posters and book covers. However, in these days of super-duper CGI effects, he looks really bland. So much so that ET, who will be thirty years old next year, still looks more convincing.

Which may be why they’ve tried to compensate his poor visual look with a cool personality. Unfortunately, they may have pushed the whole cool thing too far; the smoking, foul-mouthed character just isn’t enigmatic enough. He didn’t need to be all Disneyed up, but he could have at least been endearing.

And considering that Pegg and Frost wrote the script, it’s surprisingly dull. The usual chemistry between them just isn’t there; not only is the dialogue unusually flat, there’s just nothing memorable here. Those who like to regurgitate one-liners will struggle to find anything remotely usable in this one.

There are a few nods to other films that may put a smile on your face (if you’re a fully paid up member of the geek squad that is); most notably the tune the band are playing in the bar. But by their standards, even the in jokes are few and far between. And considering how ripe the whole Alien genre is for having some fun with, they just don’t push it far enough.

Perhaps they missed their director pal Wright, or maybe the comic duo have just had a bad day at the office. After all, you can’t expect them to churn out hit after hit all the time.

There’s no denying that there’s a real disappointment with them missing the mark here. By a country mile or two. The film is something that you wouldn’t expect from the creative minds of mssrs Pegg and Frost, and that is decidedly average. Paul is a terrestrial who’s sadly missing that little bit extra.