Swordsmen: "Your Highness"

David Gordon Green used to make ethereal, attentive small-town dramas with semi-professional casts (George Washington, All the Real Girls); now he makes busy, starry stoner comedies - like 2008's Pineapple Express - pitched squarely at the multiplexes. Unlike Steven Soderbergh, the last indie figure to vacillate between populist and more abstruse projects, Green's trajectory would appear irreversible - his next film is set to star Jonah Hill - and, were these later films not half as much fun as they are, somewhat regrettable. If the director's been led astray at all, our chief suspect would have to be Danny McBride, who had a supporting part as a yahoo in All the Real Girls and has since gone on to forge a raucous career of his own - first with the low-budget The Foot Fist Way, then on TV's Eastbound and Down - at the precise moment his tubby rabblerouser predecessor Jack Black (with whom McBride co-starred in 2008's Tropic Thunder) looks to have fallen from grace with a mighty, Gulliver-sized bump.

For Your Highness - a medieval fantasy romp we might rename The Princess and McBride - the actor writes and takes top billing over the newly Academy-dubbed James Franco and Natalie Portman, and there's possibly something touching, nay honorable, in the way Green has fashioned a star vehicle for his long-time friend. It has to be said this is about the only touching thing about the movie, which otherwise proceeds on the understanding there is no line of Olde Worlde dialogue that cannot be improved by dropping the F-bomb (or a "buttfuck", or a "cocksucker") in the very middle of it. Chaucer, for one, would love this shit. McBride's Prince Thadeous (the names are weirdly adjectival) is a pothead under-achiever living in the shadow of his dashing, square-jawed, first-born sibling Fabious (Franco). A repeated disgrace to his kingly father (Charles Dance), Thadeous is nevertheless called into battle when his brother's virgin bride (Zooey Deschanel) is snatched away by Justin Theroux's evil warlock Lazar, a stroppy virgin who has some plan or other to impregnate this fair maiden with dragon seed.

As a production, Your Highness is scrappy. Fabious is accompanied on his quest by a crap mechanical companion, and the brothers are obliged to visit a soothsayer played by the kind of rubbish puppet who turned up in Dragonslayer, Willow and Krull. (Worst. Lawyers. Ever.) The best effects are saved for a minotaur's erection. Female leads Deschanel and Portman, as a sorcerer-archer who's very nearly the pisstake of Keira-in-King Arthur that Keira-in-King Arthur deserved, adopt ridiculous English accents. It's predominantly shot in DVD-ready close-ups, and we're left in little doubt Green and every last one of his collaborators (save, possibly, McBride) are dialling down their talents: the staggeringly talented cinematographer Tim Orr, who framed entire moods and emotions with single images in Green's debut films, has here only to paint the Irish locations a stock emerald-green.

Yet the film's laziness, not wholly inappropriate for a stoner comedy, proves funny more often than not. When Lazar throws a banquet on the eve of what he terms The Fuckening, what we see is a mountain of fish fingers, mash and peas everybody on screen starts to grumble about: this is very much convenience comedy, and those of a refined palette may well baulk. Sometimes, the sloppiness is deceptive. There is, in truth, more narrative - more cause-and-effect - in McBride and Ben Best's script than there was in Green's first two movies put together; what the director has renounced in subtlety and atmospherics, he has gained as a storyteller of sorts. And as a McBride vehicle, Your Highness is a marked improvement on Foot Fist, which gave no indication of a controlling intelligence, comic or otherwise. At its best, the new film achieves that Pythonish trifecta of being silly, clever and incorrigible at the self-same time. When our heroes stumble into a boobytrap in the forest, it is - ahem - quite literally that: a community of topless Nuts and Zoo models luring warriors into mortal combat. Bawdy, yes, but I laughed - or rather, I snorted - most frequently.

Your Highness is on nationwide release.