Grade: C-

The curious thing about anarchic comedy is that to work, it needs to be very carefully structured and executed. The more slapdash or messy it is, the worse it comes off. That’s why, for instance, the Marx Brothers and Laurel and Hardy are superior to Abbott and Costello or Martin and Lewis, and Peter Sellers to Mike Myers. Or why the Beyond the Fringe troupe was preferable to Monty Python. And it’s why this adaptation of Douglas Adams’ famous series of books, radio shows and TV series is rather a flop. The main problem with the film version of “The Hitchhiker’s Guide to the Galaxy” isn’t that it doesn’t have an especially brilliant premise or lots of funny lines (though it doesn’t); it’s that, simply put, the picture is a mess–not so much in structural terms (though there are problems in that respect), but in execution. The flabby direction and forcibly wacky, totally undisciplined performances are what really do it in.

The script devised by Adams (who died in 2001) and Karey Kirkpatrick introduces us to woebegone earthling Arthur Dent (Martin Freeman, quite nondescript) as his utterly isolated house in the English countryside is being threatened with demolition for a freeway bypass. As Arthur protests, he’s whisked away to the pub by chum Ford Perfect (Mos Def, amateurish beyond belief), who tells him that he’s actually an extraterrestrial and that the whole planet is about to be vaporized to make room for a hyperspace highway; so they have to escape destruction by hitching a ride on one of the attacking vessels, manned by a lumbering race of bureaucratic giants called Vogons–who hate hitchhikers and torture them with recitations of their awful poetry. But Ford and Arthur escape to another ship, a state-of-the-art vessel that’s been stolen by an old friend of Ford’s, the totally bonkers intergalactic president Zaphod Beetlebrox (Sam Rockwell), who happens to be endowed with three arms and two heads. He also happens to be in possession of a kidnapped earth girl, Tricia (Zooey Deschanel), over whom Dent has long pined after a single meeting, and a petite robot called Marvin (little person Warwick Davis in the suit, with Alan Rickman providing the voice), a despondent, continuously whining bulbous-headed creature who bemoans his own unhappy circumstances and the company he has to keep. Beetlebrox is in search of a planet where there’s a gigantic computer (voiced by Helen Mirren) that, according to an ancient story, can provide the ultimate question about existence (having already provided the answer: 42). The search leads to a brief visit with Humma Kavula (John Malkovich), a half-human, half-mechanical spider whom Beetlebox defeated in the presidential election, along with another run-in with the Vogons, who have captured Tricia in pursuit of the president, and a session with a planet-maker named Slartibartfast (Bill Nighy), who refashions earth from a standby model once it’s revealed that the globe is the key to the ultimate question, and allowing Dent’s return to his homestead before the group takes off again for further adventures (sequel, anyone?). Running throughout are a romantic subplot involving Arthur, Tricia and Beetlebrox and periodic humorous entries from the titular guide for which Ford works, read by Stephen Fry in tones of dry superiority and accompanied by blueprint-style animation. And did we mention the song sung over the credits by dolphins as they abandon earth as the planet’s about to be destroyed?

As one might tell from all this, “Guide” is a grab-bag of sketches loosely tied together by the semblance of a plot and Fry’s spuriously explanatory observations. The tone throughout is resolutely manic, in the fashion of the old “Goon Show” or Monty Python. There are moments that spring to life. The satire of stultified bureaucracy represented by the Vogons is funny for awhile (and the creatures designed by the Henson shop are amusingly gross), a “Three Stooges” episode involving what look like flyswatters that spring from the ground to slap people in the face is hilarious at the beginning (though it pales on repetition), and Malkovich’s brief appearance poking fun at cultish religion has some punch. Nighy’s planet-maker turn, suffused with a sort of abstracted British humor, mostly works, as do a few of Fry’s contributions. Best of all is Rickman’s morose Marvin, though it’s a joke repeated a bit too often. One can also appreciate the bargain-basement quality of the effects, which often have a homely quality that’s a deliberate throwback in an era of ever more spectacular CGI visuals.

Mostly, though, the movie is oddly flat and bedraggled. That’s largely the fault of helmer Garth Jennings, who often seems to have no idea of how to keep things in narrative focus and has an unfortunate penchant for brutally oversized closeups that flatter nobody. But it also results from the fact that the cast’s efforts at zaniness almost reek of desperation. Rockwell is the chief offender in this respect; he rants and mugs to no appreciable effect, coming across as irritating rather than hilarious. But Mos Def is almost as bad; though this is a piece far removed from “The Woodsman,” in which he recently had a supporting role, his work here seems equally worthy of a high school stage rather than of the big screen. By contrast Deschanel and Freeman seem merely frazzled and ill-prepared. It’s almost as though they, like Rockwell and Def, had been thrown onto the sound stages and just told to be funny–a sure sign of directorial malfeasance and a recipe for failure. And it goes without saying that in a movie so totally artificial as this, none of them are really sympathetic characters in any way: they’re like cartoon figures, completely one-dimensional, hardly recognizable as human beings,

Of course, it probably won’t matter to afficionados that “The Hitchhiker’s Guide to the Galaxy” is a disorganized hodgepodge of skits that generate more groans than laughs. But though newcomers may not agree with Marvin’s statement as the travelers finally gaze on the planet they’ve long sought (“Incredible,” he says, “it’s even worse than I thought it would be”), they may find that it’s one of those fan-niche movies that doesn’t have much appeal for the uninitiated.