For the 30-year-old at the centre of Mack & Rita, a repurposed tanning bed and a New Age charlatan’s mumbo-jumbo summon body-switch magic: She emerges from the gussied-up contraption as the older woman she believes she truly is. The good news for the audience is that the septuagenarian is played by Diane Keaton.

This makes sense given that screenwriters Madeline Walter and Paul Welsh are vets of Brooklyn Nine-Nine. Actor-turned-filmmaker Katie Aselton, directs the material with a sunshiny SoCal sensibility and an appreciation of the terrific comic cast, though more than a few barely escape being wasted. If there’s magic here, it belongs not to the story, which wavers between clearly stated insights and an overemphasised quirk factor, but to the actors’ chemistry and the ineffable movie-star wattage of Keaton – the smile, the laugh, the idiosyncratic line readings and, not least, the fashion sense. Mackenzie, known to all as Mack and played by a cheery-yet-weary Elizabeth Lail, so much so that you might want to offer her some Geritol for iron-poor blood. She has a love of all things vintage and is the published author of a book of essays about the grandmother (Catherine Carlen) who raised her. Her agent (Patti Harrison), an amalgam of over-the-top sour expressions and social media jargon, assures Mack that books are passé and keeps her busy with minor branding opportunities as an Instagram influencer.

Mack’s best friend, Carla is about to be married, and her bachelorette weekend offers Aselton and DP Sean McElwee a chance to revel in Palm Springs’ midcentury glamour for a minute before the movie returns to a basic celebration of L.A.’s eastern stretches and downtown, old-school as well as gentrified.

The movie could have used more of their exchanges with Rita, and less of such strained slapstick as Rita’s Pilates misadventure. The latter bit aims to showcase Keaton’s undeniable physical comedy skills but aches for modulation and rhythm. Far better on that front is a delightful sequence in which Rita blisses out to shrooms. A sequence set at a beachside influencer event teeters between overkill and just-right, with Nicole Byer injecting the perfect touch of oomph.

That energy defies the movie’s product-placement neatness, and all too gently subverts its happy vision of a world of corporate ambassadors.

– Compilation