Playwright Eric O’Meara is hardly the first to have turned to a real-life 1960s rock idol in order to explore the driving ambition, extreme solipsism and high-flying excess that seem to be occupational hazards for pop celebrities cursed with talent, artistic vision and too early success. Its casualties are legion in both rock history and the literature that celebrates it.

The figure of the self-destructive rock star is so commonplace, in fact, that its venerable subcategory — the fatality-plagued, John Bonham–esque drummer — was officially inducted as a rock-martyrological cliché by the 1984 heavy-metal satire This Is Spinal Tap, which mercilessly dispatched the stereotype in a single, winking one-liner.

That kind of insight and economy, however, gives the classic Rob Reiner mockumentary a crucial step up on Dennis Wilson Forevermore: A Beach Boy’s Fable. O’Meara’s overly literal and superficial homage, which is receiving its world premiere at Santa Monica’s Promenade Playhouse, is at once so stilted by its gush of fanboy infatuation, and so undernourished of either original source material or poetic uplift, that it plays as little more than a Wiki-deep summary of the Beach Boys mythology.

In O’Meara's telling, however, even that famously compelling Oedipal narrative, in which troubled wunderkind producer-songwriter Brian Wilson (underplayed here by John Staley as a mercurial if couch-bound stoner), is artistically crippled by the Wilson brothers’ controlling and physically abusive father, Murray (a frightening Glenn Ratcliffe), gets reduced to a sidebar. Instead, the playwright argues that the band’s guiding artistic spirit should have been — or could have been — Dennis Wilson (gamely played by Ryan Boone), had the fun-loving and compulsively womanizing drummer concentrated less on the sex and drugs and more on the rock & roll part of the enduring-fame equation.

To make that case, O’Meara mostly reworks dramatic high points from the band’s story — the traumatic 1964 firing of Murray as the band’s manager; the recording of the watershed 1966 album Pet Sounds; Brian’s offstage meltdown during the SMiLE sessions — but with Dennis rather than Brian placed at the center of the action.

The play briefly comes into its own — and delivers its only convincing ring of authenticity — when dealing with Dennis’ notorious involvement with Charles Manson just before the 1969 Tate-LaBianca murders. Mark Casamento is chillingly effective as the manipulating, amphetamine-amped and aggressively menacing cult leader, and Natalia Lazarus’ maddeningly unfocused direction for once serves rather than obscures the action by lending the scenes nightmarishly hallucinatory edges.

For Act 2, Dennis Wilson Forevermore places the emphasis on forever as it gets down to the tediously repetitious and bathetic business of charting the drummer’s drug-greased death spiral and the toll taken by his louche living on three of his four marriages (Jasmin de Main, Yvonne Sayers and Amy Lucas play the unlucky wives).

Curiously, the only musical performance during the evening is Casamento’s convincing acoustic rendition of the twisted Manson ballad “Cease to Exist.” Evidently O’Meara was unable to get rights clearance to either the Beach Boys songbook or the Dennis Wilson solo album, Pacific Ocean Blue, which figures so prominently in the second act. But for such a stridently naturalistic work, the absence proves fatal. By merely insisting on Dennis Wilson’s musical genius instead of allowing the audience to hear for itself, rather than the rock & roll tragedy O’Meara intends, Dennis Wilson Forevermore clocks in as an exasperatingly inept portrait of yet another sad celebrity consumed by grotesque self-indulgence.

Promenade Playhouse, 1404 Third Street Promenade, Santa Monica; through Dec. 17. (310) 656-8070,

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