"Beyond the Sea" stars Kevin Spacey as '50s and '60s pop idol Bobby Darin, a casting decision that only makes sense when you take into account that "Beyond the Sea" was also co-written, directed and produced by Kevin Spacey. Darin was 37 when he died in 1973, eight years younger than Spacey is now. That's the same number of years that separated him from his wife, Sandra Dee, played here by 21-year-old Kate Bosworth. Understandably prickly and self-conscious about this, the movie kicks off with an astonishingly preemptive sequence that attempts to disarm any incoming criticism by appropriating it, ACT UP style. (He's here. He's middle-aged. Get used to it.) During what we're told is the anniversary party of his 10th year in show business, Darin interrupts himself mid-song, berates the band and film crew, and stalks off the set. In no time, he's accosted by a gangly reporter in a fedora, who gutlessly calls after him, "Isn't the truth that you're too old to play this part?" Darin's brother-in-law, Charlie (Bob Hoskins in full Fred Flintstone mode), jumps to his defense. "He was bornda play da part! Giiieeeett outta here!" Then he turns to the star with a disbelieving shrug: "How can you be too old to play yourself?" Spacey responds with an enigmatic smile, and you get the feeling he had a vocal support system as this project went forward.

"Beyond the Sea," which takes its title from one of Darin's hit songs ("Mack the Knife" and "Splish Splash" are among some of the others) is constructed as an autobiographical musical fantasy directed by Darin with the help of his inner child, played by the kid who plays him as a kid (William Ullrich). Occasionally, they disagree. But as Darin tells his young self, "Memories are like moonbeams; we do with them what we want." Movies are kind of like moonbeams too, and what Spacey wants to do with his is sing and dance in a crazy suit. It's not that he doesn't pull it off; his singing and dancing are creditable; and the effect of the first big dance number is mostly one of not unpleasant astonishment at seeing him hoofing it on the pavement, jazz hands aloft. But it doesn't really add up to much.

Spacey doesn't shy away from portraying Darin as a self-aggrandizing, self-mythologizing megalomaniac, but not only does he withhold judgment, he also withholds analysis. Nor does he really deliver much insight into the particular performer's rise and — would you call it a fall exactly? Not knowing more about the performer's life than the movie showed, I can't quite be sure. For all of Darin's heart-to-heart chats with his young self, "Beyond the Sea" keeps the down-moments feisty and the explanations simple. He gallops through the highlights and lowlights of the performer's life and career and reduces his smugness, drive and airtight self-involvement to a single source: the heart defect (never raised to the level of symbol) that turned even his basic survival into a triumph of will.

Hindered by its own theatricality, "Beyond the Sea" feels at once hermetic, defensive and corny. John Goodman, Peter Cincotti and Hoskins, as Darin's manager, band-leader and "valet," spend most of their time assenting, harrumphing and raising their voices in defense of the man they lovingly refer to with a vulgarity. Bosworth's luminous beauty fails to compensate for other limitations. (When Darin lashes out, "Melvyn Douglas is married to a congresswoman, and I'm married to Gidget!" it only highlights how unlike Gidget Bosworth seems.) Inevitably, the whopping 24-year age difference between Spacey and Bosworth adds an unwanted creep factor — literally to the point that their utter lack of chemistry actually comes as a relief. It also lends probably unintended connotations to the wedding night scene in which Sandy collapses into a heap of pre-bedtime hysteria, and Bobby rushes into the bedroom brandishing a sword.

Just how unself-aware was he? Here's a clue: Voice-over narration fills us in on the social and cultural upheavals of the '60s, and the waning star's newfound interest in politics, and next thing, "Bob" Darin is hopping a trailer and hitting the sand to try his hand at protest songs.

Fair enough. Until he returns to civilization and tests them out — along with his new mustache — on the regulars at the Copacabana. This might have been a riotously funny and painfully intimate scene — what in the world did Darin think he was doing? But Spacey glosses over the absurdity of it, siding with Bobby's contempt of the audience, and apparently failing to see the humor and pathos inherent in the singer's attempt at reinvention.

Instead of pathos, "Beyond the Sea" offers caramel-coated sentimentality, especially in Darin's mother, Polly (Brenda Blethyn), and sister Nina (Caroline Aaron), who keep the spirit of Ye Olde Brooklyn alive for him as his star rises. Blethyn's part is pure cornball — she's an old vaudevillian whose husband was a gangster. But Nina is a genuine grotesque who supplies the film's only raw, if difficult to watch, moments. But all in all, the timing of this release seems especially unfortunate, coming as it does on the heels of the thoughtful and penetrating biopics "Ray" and "Kinsey," which went eloquently beyond the sea of clichés about flawed geniuses to create intimate, lifelike portraits of brilliant, damaged men. Compared to them, "Beyond the Sea" just looks like a musical about a jerk.

'Beyond the Sea'

MPAA rating: PG-13 for some strong language and a scene of sensuality

Kevin Spacey...Bobby Darin

Kate Bosworth...Sandra Dee

John Goodman...Steve Blauner

Bob Hoskins Charlie Cassotto Maffia

Brenda Blethyn...Polly Cassotto

Greta Scacchi...Mary Duvan

Lions Gate Films presents an Archer Street / QI Quality International / Trigger Street production, released by Lions Gate. Director Kevin Spacey. Producers Arthur E. Friedman, Andy Paterson, Jan Fantl, Kevin Spacey. Screenplay by Kevin Spacey and Lewis Colick. Director of photography Eduardo Serra. Editor Trevor Waite. Costume designer Ruth Myers. Musical director John Wilson. Production designer Andrew Laws. Choreographer Rob Ashford. Running time: 1 hour, 58 minutes. Exclusively at the ArcLight, 6360 Sunset Blvd., Hollywood, (323) 464-4226, and Laemmle's Royal, 11523 Santa Monica Blvd., L.A., (310) 477-5581.