"Harmony" confirms Barry Manilow's musical theater chops. The pop legend invests this biotuner of the Comedian Harmonists -- a real-life German male sextet, pre-WWII toasts of two continents -- with graceful, catchy melodies and a reasonably period, lightly jazz-influenced style, especially in the performance sequences. He likely could pen character-based songs, too, if he were handed characters to write for. But despite reputed decades of development, the storytelling remains woefully inadequate to the saga's potential, let alone worthy of the talents on view at the Ahmanson.

Six cats from diverse backgrounds (three Jews, three Gentiles) combined a Yank-inspired early doo-wop sound with knockabout dance and physical comedy. Essentially, the Four Seasons met the Ritz Brothers in a lightning ascendancy, eventually crushed by Nazism's simultaneous rise. To play them, the production (from Center Theater Group and Atlanta's Alliance Theater) has assembled an extraordinary set of young kids who own that stage with vivacity, panache and terrific pipes. There's no difficulty believing in the troupe's legend.

Believing in the troupe is another matter. We're led to expect a passel of disparate individuals who will pull together into a cohesive whole, even as the outside world falls apart. Josef a/k/a "Rabbi" (Shayne Kennon, fulfilling a "Jersey Boys"-like narrator function) himself sums it up: "Amidst all the horror, and despite our squabbles, we found harmony."

But librettist Bruce Sussman's key decisions devastate this solid premise. Incredibly, we never get to see the Harmonists find and develop their signature style; it springs full-blown in Berlin alleyways and never changes. Worse, the libretto assumes the guys behaved in exactly the same goofy, jokey manner offstage and on. There's neither reality nor contrast in their interactions, especially since each fellow is permitted one trait apiece, if that.

Rabbi, for instance, is a cocky Jolson clone. One guy's grumpy; two are dewy screamers (literally); one's a suave heartthrob and the group's founder is earnest. They're like seven -- okay, six -- dwarfs circled by a Snow White (Leigh Ann Larkin as Rabbi's blond inamorata) and Rose Red (Hannah Corneau as the resident Emma Goldman). All indeed behave like fairytale characters much more than actual persons haunted by history.

Those "squabbles" Rabbi mentions must've been cut during La Jolla or Atlanta tryouts, because the prevailing mode is adolescent cutup. In a useless backstage "Officer Krupke" farrago, one lad rehearses revealing his career to his parents. The great Marlene Dietrich (Lauren Elaine Taylor) is rudely caricatured as an untalented dimwit just so our boys can wax smartass while singing backup. The occasional serious moment plops into scenes like an errant sandbag.

Act two, as Hitler takes power, starts badly for Western Europe and no better for "Harmony." Ninety minutes of principals frisking like puppies in a sack ill-prepares them, or us, when events turn dark. Characters make abrupt, unprepared-for about-faces and wail in anguish, engaging in passionate arguments whose sense is impossible to follow.

Sussman proves a capable lyricist in "Every Single Day" and "In This World," power ballads which retain delicacy without overpowering. The title tune's signature "oom-pah-pah" tickles the fancy and sticks in the memory.

But oh, that script. Sussman and helmer Tony Speciale must think none of us has ever heard of Nazi Germany or anti-Semitism, because they interject numberless historical nuggets solemnly intoned on the sidelines ("Attention! The following Nuremberg Laws will be enforced"), and threats delivered by oily Gauleiters in cliched encounters verging on camp. Protest song "Come to the Fatherland" is a cheesy embarrassment.

"Harmony" looks grand in Tobin Ost's supple sets and elegant costumes, but it never recovers from its maladroit emphases. We want to follow complex characters coping with high-stakes peril, and instead we get hysterical flapping and a stilted primer on the roots of World War II.

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