Changeling children, nurturing booklovers, and paternal coincidences are (as in Matilda the Musical) key tropes in Bright Star, the new musical by former New Bohemians frontwoman Edie Brickell and movie star-turned-funny-banjo player Steve Martin. Embracing kiddie-lit sentimentality is a problem for this ostensibly serious show about hardscrabble life in the early 20th century American South. Further raising an unmet bar, half the characters in Bright Star are supposed to be on staff at an esteemed Southern literary magazine, something along the lines of The Sewanee Review.

You’d hope that musical where people drop names like Hemingway and Eudora Welty and Thomas Wolfe would at least have decent dialogue and an absorbing plot. Bright Star does not. I doubt literary script doctors can salvage this one, certainly not before Broadway previews begin on March 24.

“Which words should I cut, Ms. Murphy?” aspiring writer Billy Cane asks his eagle-eyed editor. “The superfluous ones,” she says dryly, and that’s as witty as things get. By way of suspense, audiences can wonder for about two scenes whether Billy will marry Margo, the bookstore clerk back home in Hayes Creek, or Lucy, the worldly-and-wise copy editor who likes to down gin fizzes in the big city of… Asheville?

If theater critics had their say, he’d pick Lucy, as played by Emily Padgett. The spritely blonde was last seen at the Kennedy Center playing one half of conjoined sister act in Side Show. She provides the closest jolt to a mint julep when she sings and does a modified Charleston in “Pour Me Another,” but all too quickly ex machina cuts in, as it so often does in this musical. Billy hops on a train back to Hayes Creek, where he has the good fortune of finding a bride, a story for his first novel, and his family heritage all within five minutes on the same front porch.

That inviting porch is the best thing about Bright Star. Inside the see-through frame of the rotating house is an outstanding bluegrass ensemble, augmented by additional musicians playing in the catwalks. The sound is pristine too, as it often is in the smaller, retrofitted Eisenhower Theater. Brickell and Martin are decent musical collaborators; several numbers are adapted from their 2013 album, Love Has Come for You. Oddly, most lyrics on the record are more clever than those sung onstage. “When you get to Asheville, write me a letter,” Margo opines in Bright Star, while Brickell sang, “Send me an email,” and went on to tell her lover about Goldie’s latest dogfight, neatly mashing up old-timey tropes with present-day communication methods.

If only that same quirky creativity enlivened Bright Star, too. The musical is alternatively set in both 1923 and 1946, and the initial storyline is driven by cliched Southern Baptist bad guys who thwarted a romance much earlier in Ms. Murphy’s life. (It should be said that Carmen Cusack plays both her teenage ingénue and Anna Wintour-esque roles well.) Besides Billy’s bride-to-be, there’s another heavily telegraphed Big Reveal at the end of the musical, one that wraps everything up neater than a Laura Ashley bow. “It’s too corny for Broadway,” commented the patron behind me after the curtain came down at the Kennedy Center. Remember that Broadway is the sort of place where shows with characters named Matilda Wormwood and Miss Honey can run for years. Bright Star, I fear, is yet another D.C.-made show that will quickly fade from the New York marquees.

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