Mack (Elizabeth Lail) is the sort of person that you might call an old soul. She was raised by her grandmother and has long been attracted to the sort of to-hell-with-it attitude cultivated by women of a certain age. She grew up to be a writer whose first book – about her relationship with her grandmother – was fairly successful. Alas, one book does not a career make. Mack makes her living now by piecing together various endorsement deals, posting products on social media to pay the bills at the behest of her agent.

Mack’s best friend Carla (Taylour Paige) is getting married, so much to her chagrin, she has to go and do bachelorette party things in Palm Springs; she enlists her neighbor Jack (Dustin Milligan) to look after her dog Cheese and heads out to the house Carla’s mother Sharon (Loretta Devine) has procured for them for the weekend.

After being exhausted by standard bachelorette party shenanigans, Mack decides to peel off and do her own thing – in this case, a pop-up relaxation tent manned by a disinterested New Age-y type named Luka (Simon Rex). She lies down, but when she gets up again, Luka is gone … and so is 30-year-old Mack.

Instead, we see Mack at 70 (Diane Keaton). After her initial panic, she makes her way back to the house and confesses to Carla what has happened. With no idea how to change back, she returns to her apartment, where she encounters Jack and tells him that she is Mack’s Aunt Rita.

Cue the hijinks.

Mack/Rita’s efforts at maintaining her social media presence leads to an unexpected explosion of popularity surrounding the Rita persona. Rita becomes part of Sharon’s wine club, hanging out with other delightfully self-assured older ladies. And something starts bubbling with Jack, as the two find themselves hanging out more and more.

But with so much going on, Mack/Rita starts losing sight of other important relationships. And while she might believe that she has found her true self, she must also confront the reality of just how much will have been missed.

“Mack & Rita” is a charming, funny film, a movie that is both familiar and unlike the usual fare. Think “Freaky Friday” meets “Harold and Maude” and you’re in the neighborhood – it’s a movie that plays its premise for laughs, of course, but also finds ways to prod at some deeper themes along the way.

With a less steady hand at the wheel, this movie could have been crass, packed with stereotypes played for cheap laughs. Instead, Aselton finds the humor without punching down, navigating the delicate nature of what it means to age while also landing plenty of good jokes. It’s funny without being mean-spirited. One gets the impression that Aselton has had some strong-minded older women in her life along the way – there’s a sense of respect throughout, though again, that respect does not get in the way of the laughs.

Speaking of respect – Diane Keaton is here. Keaton is a legend, an iconic figure in the history of cinema who in many ways invented some of the rom-com tropes at play in this film. Few actors have ever managed to blend franticness and dignity onscreen like Keaton; Aselton takes full advantage of both that talent and that history. It’s a breezy performance, but also one that grounds the premise in a way that allows the audience in.

Aselton has surrounded Keaton with performers doing first-rate work. The chemistry between Keaton and Dustin Milligan is palpable; the two of them click in a wonderfully engaging way (and it’s here that I’ll note the deft way in which Aselton handles the age difference, in that she treats it essentially the way that Hollywood has traditionally treated this dynamic when the genders are reversed – not as a joke, but as a perfectly normal, reasonable relationship). Lail kind of gets short shrift in some ways, but does good work when she’s there. Paige is very good, as are the rest of her bridal party cohort. And the wine club ladies – Devine, Wendie Malick, Lois Smith and Amy Hill – are a collective delight.

(Oh, and there’s a fantastic voice cameo that I won’t spoil.)

“Mack & Rita” might not be what you think of when you think summer movie – nobody wears a cape and nothing explodes, after all – but perhaps you should change your mindset. After all, shouldn’t we all want to see funny, heartfelt movies with good performances and something to say, in the summertime or otherwise? In the end, you’re only as old – or as young – as you feel.

[4 out of 5]