Clueless review – all back to the 90s for a musical of the movie? As if!

What do you get if you cross a high-school movie with Jane Austen’s comedy of manners? Clueless, of course. The 1995 film was inspired by the plot of Emma, in which a frivolous young schemer falls for the serious-minded landed gent next door. This musical version again transposes the story of misguided friend-zoning to Beverly Hills High but where the film pulled off the outlandish melange of Austen and Americana, Rachel Kavanaugh’s production is a more lumbering hybrid.

Emma is reborn as Cher (Emma Flynn), a wealthy LA valley-girl with an ensemble of privileged high schoolers around her who may well be branded nepo babies today. She manipulates grungy new girl Tai (Romona Lewis-Malley), all for the greater good of transforming her into a paragon of high-school popularity. Josh (Keelan McAuley), meanwhile, is the serious-minded chap who is helping Cher’s lawyer father with his cases and has a teasing relationship with her that builds into love.

We are definitely in the 1990s because people are using Walkmans, talking lavishly about their pagers and brandishing brick-like mobile phones. Amy Heckerling adapts her own screenplay, sticking closely to the original, including the jibes about high-school cosmetic surgery, although mercifully Cher’s obsessive calorie talk has been excised.

Needs more fizz … l to r, Emma Flynn (Cher), Keelan McAuley (Josh) in Clueless. Photograph: Pamela Raith

The songs, composed by KT Tunstall, are disappointingly flat-footed except for two belters accompanied by comically energised choreography. Reasonable Doubts, sung by Josh and the ensemble, is a magnificent ode to teen jealousy, while I’m Keeping an Eye on You, performed when Josh turns up to a dance to watch over Cher, is as winning. If the score could fizz with more numbers like these then what a blast this show might be. But the lyrics by Glenn Slater too often serve as exposition rather than raising the emotional drama.

The characters are peculiarly flat. Cher has flecks of Elle from Legally Blonde, Tai sounds like a cross between Bette Midler and Rizzo from Grease, Cher’s love interest Christian (Isaac J Lewis) speaks like a 1950s cliche. Josh is obnoxiously judgmental of Cher with the song Human Barbies, in which he accuses her of treating others like dolls. Maybe if he had watched Greta Gerwig’s Barbie, he might see things differently, although the script references nothing outside its 90s bubble – even when it is crying out for sly sideways glances, such as the moment in class when Cher debates the all too Trumpian question of whether immigrants should be admitted to the US.

Still, the performances are strong, full of grinningly nasal high-school energy. Flynn nails the comedy in Cher’s failed seduction of Christian, while Blake Jordan, as the stoner skateboarder Travis, is sweetly portrayed, too. There is also some consolation in Mikiko Suzuki MacAdams’s clever set design, which sees sofas transforming into cars and a backdrop of the LA skyline changing colours to suit the mood. But this is a paler version of the film, laden with the retro “naff” factor but having less creativity and soul. The theatrical deification of the 1990s evidently continues apace, for the worse.

• At Trafalgar theatre, London, until 27 September