The last big, blustery, effects-driven, mindless entertainment of the year has arrived, and Cowboys & Aliens is an exemplar of what the Hollywood machine is capable of. Which is not a particularly good thing. The mash-up looks good on paper: one retro-cool genre (the western) married to a CGI-friendly genre (alien invasion sci-fi) with obvious nudge-nudge cheekiness. The title tells you everything you need to know. The pitch meeting would have gone something like, "So, space aliens invade during the 19th century in the old west, populated by cowboys. We'll call it Cowboys & Aliens!" Isn't that clever?

As films rarely begin with a script these days - they start with a producer, a concept and a movie star - and the parts are cobbled together by calling in heavy hitters with the requisite experience (a necessity when you're dealing with $160 million, Cowboys & Aliens' reported budget) Cowboys & Aliens seemed like a sure bet: it was written by a committee made up of Alex Kurtzman and Roberto Orci (Fringe, Star Trek), Lost and maestro Damon Lindelof, and Mark Fergus and Hawk Ostby (Children of Men); visual effects were churned out by ILM (absolutely everything); Matthew Libatique (The Fountain, Black Swan) was tapped for cinematography - key to westerns; it stars Daniel Craig (James Bond!) and Harrison Ford (Han Solo!!) in a cast that included genre veterans Sam Rockwell (Moon), Clancy Brown (Highlander) Keith Carradine (Dexter), Walton Goggins (Justified), and Raoul Trujillo (The New World); and it has 17 producers, including Brian Grazer (24), Ron Howard (Apollo 13) and some dude called Steven Spielberg. At the helm: minor Comic-Con deity Jon "Iron Man" Favreau. Well, now.

The problem with all these so-called geniuses is the distillation of vision that comes with that kind of all-star crew. Cowboys & Aliens is disjointed, baffling, and too enamored of its own witty premise to get any single element of it right. The western, by definition, is loaded with such symbolism and iconography it's like catnip to filmmakers looking to make a point in a fresh way. The framework has been used time and again, most recently in genre mash-up Firefly, but without a keen sense of direction the conventions of the western become a burden. And without a sense of respect (Unforgiven, Deadwood) or loving sense of humor (The Adventures of Brisco County Jr.), grafting it onto a form as equally rigid as sci-fi is asking for trouble.

A stranger we eventually discover is a wanted man called Jake Lonergan (Craig) wakes up in the Arizona desert, confused and with an odd looking doohickey strapped to his wrist. After putting a gang of bandits in their place in spectacular fashion, Lonergan wanders into Absolution, a frontier mining town ruled with an iron fist by Woodrow Dolarhyde (Ford). You know this is a badass town because fantastically Old West names like Absolution, Dolarhyde, Doc and Taggart are represented. Anyway. Moving on.

It turns out the people of Absolution are a suspicious lot, and matters aren't helped when "demons" swoop down from the sky one night, unleash a reign of terror and fly off with many of the townsfolk. But aha! The doohickey on Lonergan's wrist can blast the invaders to bits. This all unfolds in the first hour of so, and does so with a certain degree of aplomb - even if it is as serious as a heart attack and totally without levity. It's almost as if Favreau and Co. were so determined to transcend the goofy title they overcompensated with seriousness. Craig is suitably stoic as The Stranger/Lonergan, but is so dour there's no entry point for viewers, and he doesn't look completely comfortable in his chaps. And Ford, verging on decrepitude (watching him haul himself up onto his steed is wince-inducing), looks bored, flatly growling out his flat dialogue if that's possible.

It's in the second half, when the clichs come out in full force, that the film starts to wobble even more - and that's long before we get a good look at the (now) conventional aliens. You know, the ones that look like the beasties from Alien, Cloverfield, Super 8 and every other alien of the last three decades. Seriously, is there a latex and runny petroleum jelly warehouse to order these things from? Anyway. Part two is when, predictably, the townsfolk, a gang of outlaws, and a sect of Apache warriors (!), led by the predictably enigmatic Ella (Olivia Wilde) band together to stage a rescue of their kin.

It's also here that Cowboys & Aliens' inherent falseness starts to shine through, not helped in the least by cloying (a positively 21st century redemption for Dolarhyde vis--vis his Apache hired gun) and narrative convenience; 1800s-era humanity will be crushed by the intergalactic travelers. No wait! Lonergan has that doohickey! Phew. It's doubtful anyone was expecting the second coming of The Searchers with a chaser of District 9, but Cowboys & Aliens is so constructed, so meticulous in its Cinemascope rides across the plains and back-lit silhouetted solitary gunslingers that it forgets to be a movie that says anything - which The Searchers and D9 most definitely did. The science fiction elements are equally claptrap, and the aliens aren't the only thing that look recycled.

A strong supporting cast infuses the whole affair with fleeting sparks: Rockwell as the saloon owner Doc looks comfortable in the apron and spectacles; Paul Dano (There Will Be Blood) as Dolarhyde's bully son is creepily desperate; and Brown could read the Yellow Pages and make it compelling. Sadly, they can't raise the film any higher than its high concept play-acting will allow. Favreau's best mainstream work, in Iron Man and Elf, happened when he applied his indie attitude to a summer tentpole property - kind of like Kenneth Branagh bringing a touch of the Bard to Thor. Cowboys & Aliens didn't need to be so serious to avoid self-fulfilling prophecy, and it certainly didn't need an army of heavyweights to give it direction.

At least it wasn't in 3D.

Cowboys & Aliens opened in Hong Kong on Aug 25