Bringing a whoosh of comic energy to a movie in which John Malkovich is already disporting himself at full flutter seems an unlikely feat, but Emily Blunt manages it in "The Great Buck Howard." She plays a young publicist assigned to scare up press coverage for a touring "mentalist" (not magician, thank you) whose glory days are far behind him but whose ego remains unfaded. Back in the '70s, when he was a regular guest on "The Tonight Show" (where host Johnny Carson dubbed him "The Great"), Buck Howard (Malkovich) was a star, a household name. Now he plies his trade — mind-reading, hypnotism, very bad singing — in places like Bakersfield and Cincinnati. But he still gives his all ("I love this town!" is how he greets every audience), and he still holds out hope for a rekindling of the media glow in which he once basked. Valerie Brennan (Blunt) is the latest PR lackey to inherit the stewardship of this seemingly hopeless quest.

The movie would be altogether more energetic if it weren't framed by a bland coming-of-age story involving a young man named Troy Gable (Colin Hanks). Troy is a law-school dropout who wants to become a writer; to pay the bills, though, he's accepted a job as road manager for Buck Howard, a figure with whom he's been fascinated since childhood. As an actor, Hanks has something of the warm repose that made the young Henry Fonda such an appealing screen presence. Here he's a stand-in for the movie's writer-director, Sean McGinly, who once worked as a road manager for an actual famous mentalist, the Amazing Kreskin. But putting Troy at the forefront of the story, where he obscures the more vivid performances of Malkovich and Blunt, unbalances the film. When Buck responds to the news that he's to be interviewed by an Internet reporter by hissing "I don't even know that paper," you want to hear more — and Hanks' character isn't conceived in a way that would allow him to top a line like that. McGinly himself realizes what a pallid mope Troy is. Encumbering Hanks with a woozy, meaning-of-life line like "I want to spend the time I have doing something that makes my heart race" turns him into an instant straight man, allowing Blunt's Valerie, who has her randy eye on Troy, to swoop in with "That really turns me on."

Blunt has the advantage of having a crisply defined character to play. Valerie is smart, ambitious and witheringly unsentimental, and Blunt uses her caustic deadpan (and some of McGinly's sharpest writing) to take over several of the scenes she's in. She's positioned to provide the movie's token romantic interest, and it's a treat to watch her muddle it. (Having blurted out to Troy that she has a boyfriend back in L.A., she instantly regroups: "Forget I said that," she says, leaning in for a one-night smooch.)

The role of a flamboyant has-been seems so custom-tailored for Malkovich that his actual performance feels anticlimactic. The cheesy ascots and awful orange blazers are perfectly in place, the graying hair is coiffed with adequate vanity, and when he spots a long-awaited profile in a magazine — one that turns out to examine him as a resident in "the minor leagues of showbiz" — we await the fuming meltdown that must surely follow. Malkovich is a terrific performer, but the movie's listless pace drags him down, and the character of Buck never quite comes into focus. There's a running joke about his sexual ambiguity (he dedicates his terrible songs to "a once very great friend of mine," the famously gay "Star Trek" alumnus George Takei, who later turns up for a huggy reunion), but it's so unformed that it never pays off.

The film is padded with familiar faces. Tom Hanks (who co-produced) plays his son Colin's dad to minimal effect, and Steve Zahn and Ricky Jay are oddly underutilized — Zahn in the role of a hick limo driver with a bandido mustache, Jay as Buck's manager. Also passing through in cameos are Tom Arnold, Conan O'Brien and Jon and Martha Stewart. And still the movie feels underpowered. Surely it would have been livelier if we saw Buck through Valerie's eyes, rather than Troy's. Valerie knows who she is, and she's a quick, funny study at sizing other people up. We're never sure who Troy is, or why we should care. We just know he's in the way.

Don't miss Kurt Loder's reviews of "The Haunting In Connecticut" and "American Swing."

Check out everything we've got on "The Great Buck Howard."

For breaking news, celebrity columns, humor and more — updated around the clock — visit MTVMoviesBlog.com.