Starring Zac Efron, Leslie Mann, and Matthew Perry. Rated PG.

In this goodhearted teen pleaser, Matthew Perry plays alleged grownup Mike O’Donnell, pushing 40, stuck in a dead-end job, and just about to lose his family due to inattention and general midlife ennui. That changes when Mike goes through a Back to the Big Future on Freaky Friday transformation and turns into his former self, as embodied by shirtless Zac Efron.

That’s only one of the credulity-stretching elements in a tale that insists—once he returns to fast times at his old high-school stomping grounds—that no one in the same sphere would recognize a guy who was Mr. Charisma less than 20 years earlier. That’s particularly baffling when it comes to a boyhood friend, Ned, who idolized him to the point of sexual confusion. Now a nerd tycoon (deftly played by Thomas Lennon), this pal gets busy pursuing the school’s sexy principal (Melora Hardin).

Meanwhile Mike, once again a basketball big shot, spends an increasing amount of time with shy son (Sterling Knight), sullen daughter (Michelle Trachtenberg), and—most creepily—with wife Scarlett (squeaky-voiced Leslie Mann), who at least senses something awfully familiar about this beautiful and ardent young man.

I wish Jason Filardi’s intermittently witty script spent less time dreaming up ways for Mike to act noble—if that’s what you call sanctimonious abstinence speeches aimed at your own children (in Margaret Cho’s sex-ed class, no less). Neither he nor generally smooth director Burr Steers seem to care about the strangeness of Mike’s rebirth experience and what it might mean to him, aside from moralistic problem-solving.

There’s not enough magic to the movie, but the fact that Efron turns in such a nuanced, nonmusical performance—he does Perry better than Perry—bodes well for his particular future.