It’s theoretically possible to turn the “Bonnie & Clyde” saga into a conventional musical play, but the eponymous tuner at La Jolla Playhouse hasn’t found the magic formula. Flummoxed by the challenge of creating likable, sympathetic protagonists while remaining truthful to the facts of their vain, pointless Depression-era death spree, the creative team falls back on tired character types and clashing cliches.

The show catches the time and place visually. Designer Tobin Ost’s handsome, Steinbeck-worthy unit set, featuring rough boards and sliding panels, is accentuated by Aaron Rhyne’s striking projections and Michael Gilliam’s lighting effects, offering lovely “Grapes of Wrath” tableaux throughout.

And composer Frank Wildhorn comes up with an evocative string of bluegrass and gospel melodies orchestrated (by John McDaniel) with melancholy undertones of loss — at least until late in act one, when he starts indulging his penchant for generic, identical-sounding power ballads that could be transplanted into any show of any period.

But nothing can compensate for a plot failing to make sense from scene to scene.

The leads are introduced so cutesy-poo they might be playing “Bugsy Malone.” Someone seems determined to remind us of Laura Osnes’ leap to fame in the “Grease” reality TV show, for her Bonnie is pure Sandy Dumbrowski — pert and perky, without a trace of lewdness, carnality or Texas dust under her nails. She might as well be encountering Danny Zuko when she and Clyde (Stark Sands) “meet cute” as he’s trying to steal her mom’s car, sheepishly sliding out from under the leaky engine.

Sands’ Clyde is a Pepsodent-smile charmer, a burgeoning Harold Hill with vague dreams of riches and notoriety. Librettist Ivan Menchell throws in an occasional foreshadowing of the murderer-to-come, but the transformation from dude to killer is as difficult to swallow as Bonnie’s shift from A-student to bad girl.

Meanwhile, Clyde’s brother Buck (Claybourne Elder) and sister-in-law Blanche (Melissa van der Schyll) are written as a stock second couple. Their comedy is labored, and doesn’t help them when their involvement proves deadly.

This Bonnie and Clyde fall in love because the script says so, not because of any erotic chemistry between the players. After a brief hint of Clyde’s impotence, we’re inundated by lyricist Don Black and Wildhorn’s bombastic love songs (“You Love Who You Love”; “I’ll Never Leave You”), so one supposes we’re to “buy” their romance. But for all Sands and Osnes’ clutching and rubbing, they fall short of conveying a passion of the ages, and his thin tenor doesn’t hold its own against her Broadway belt.

Menchell contrives a love triangle with a local deputy (Chris Peluso) carrying a torch for Bonnie, but a potential delicious irony — that Bonnie might reject a virile lawman in favor of an impotent rogue — comes to naught when Deputy Ted proves no more manly than Clyde. The rejected swain is reduced to providing exposition and looking grim.

This tuner really gets derailed when the murders begin. Offsetting helmer Jeff Calhoun’s copious blood effects (he’s doubtless seen some Martin McDonagh), Menchell keeps tossing in details designed to make us feel for the poor kids: They’re victims of society; they’re misunderstood; they love their families; “he’s good,” “they’re really good” (this sentiment repeated constantly). Clyde robs a bank teller of his own wallet and gives the cash to indigent depositors: awww, he’s just a sweet ol’ Robin Hood, as he and Bonnie bicker over who ought to get top billing.

But as the bodies pile up, it becomes difficult and finally morally untenable to embrace this Bonnie and Clyde — one minute feral, the next life-affirming with no overriding logic to the shifts.

The Arthur Penn film painted the duo as a pair of jaunty, clueless nihilists right out of Godard’s “Breathless.” That take on the subject has the benefit of consistency and unity, far preferable to this catch-as-catch-can attempt to both exploit and whitewash psychopaths through glib sociological excuses and shallow psychological explanations.

Bonnie & Clyde

Mandell Weiss Theater, La Jolla, Calif.; 504 seats; $78 top

  • Production: A La Jolla Playhouse presentation of a musical in two acts with book by Ivan Menchell, music by Frank Wildhorn, lyrics by Don Black. Directed and musical staging by Jeff Calhoun. Music supervision and direction, orchestrations, incidental music, vocal arrangements, John McDaniel.
  • Crew: Sets and costumes, Tobin Ost; lighting, Michael Gilliam; sound, Brian Ronan; projections, Aaron Rhyne; fight direction, Steve Rankin; production stage manager, Paul J. Smith. Opened, reviewed Nov. 22, 2009. Runs through Dec. 20. Running time: 2 HOURS, 35 MIN.
  • Cast: Clyde Barrow - Stark Sands Bonnie Parker - Laura Osnes Emma Parker - Mare Winningham Blanche Barrow - Melissa van der Schyff Buck Barrow - Claybourne Elder Sheriff - Wayne Duvall Ted - Chris Peluso With: Leslie Becker, Daniel Cooney, Courtney Corey, Michael Covert, Victor Hernandez, Michael Lanning, Michael Mulligan, Carly Nykanen, Mike Sears, Jessica Watkins. <BR> Musical Numbers: "Short Order World," "This World Will Remember Me," "The Long Arm of the Law," "You're Goin' Back to Jail," "This Never Happened Before," "God's Arms Are Always Open," "You Can Do Better Than Him," "You Love Who You Love," "Sixteen Years," "This World Will Remember Us," "The Long Arm of the Law" (reprise), "I'll Never Leave You," "You're Not Goin' Back to Jail," "What Was Good Enough for You," "Bonnie," "The Devil," "These Are What You Call Guns," "Dyin' Ain't So Bad," "How 'Bout a Dance," "God's Arms Are Always Open" (reprise), "The Long Arm of the Law" (reprise), "This World Will Remember Us" (reprise).
  • Music By: