The beguiling Andie MacDowell, a leading lady in films like “Groundhog Day” and “Four Weddings and a Funeral,” has taken on more supporting roles in the past several years, from “Ready or Not” to “Magic Mike XXL” to the Netflix series “Maid,” opposite her daughter, Margaret Qualley. While she’s always memorable, it’s nice to see her step into a leading role once again (and a non-romantic one at that) with “My Happy Ending,” a heartfelt comedy-drama directed by Tal Granit and Sharon Maymon.

“My Happy Ending” is written by Rona Tamir, based on a play by Anat Gov. The events unfold over several hours in a single setting, which exposes the theatrical roots of the story, though Granit and Maymon add a touch of magical realism to liberate the film’s cinematic potential.

MacDowell stars as Julia Roth, an American mega-star who travels to a small British clinic for chemotherapy. Her star is on the wane, having just endured a West End flop, and she’s attempting to go incognito at the chemo clinic. She hasn’t told anyone, including her manager or daughter, about her diagnosis of colon cancer, and she thinks she can muscle through a few rounds of chemo on her own without being discovered. Privacy proves to be a challenge at the clinic, which doesn’t have private rooms, only curtained off areas, but it turns out that the lack of secrecy is exactly what Julia needs.

Across the curtain are three women: the wacky, wig-swapping Mikey (Sally Phillips); a wise, curmudgeonly older woman, Judy (Miriam Margolyes); and a quiet but busy young mother, Imaan (Rakhee Thakrar). After a few awkward exchanges in which it becomes clear that every conversation can be overheard in the room (often used to comedic effect), Julia surrenders to her surroundings and finds comfort in these women, who understand, better than she does, the challenges she’s facing.

The premise of “My Happy Ending,” set in one room over one day, is somewhat slight, but there’s nothing insubstantial about a woman coming to a profound realization about her life thanks to a surprising encounter with unexpected new allies. MacDowell brings her signature soulful charm to the role of Julia, who starts out as guarded and fearful, and blossoms into a powerful advocate for herself. Plus, casting Phillips, whom you’ll recognize as one of Bridget Jones’ best friends, is like a cinematic cheat code; her comic energy is undeniable, but here she is allowed to color in all the shades of the emotional rainbow, from euphoria to regret.

Granit and Maymon allow the characters and the audience to escape the clinic through the women’s shared guided visualizations, which they call “holidays,” escapist fantasies to an island rainforest, or Burning Man, or just back home. Julia’s “holidays” are scattered, but as she hones in on what would make her happy, not impressing the other women or pleasing her strident longtime friend and manager, Nancy (Tamsin Greig), it helps her to understand what she wants to do in the face of such a daunting diagnosis. The support of the other women allows her to speak her truth and her choice clearly to both Nancy and her doctor (Tom Cullen).

“My Happy Ending” may at times feel modest, but the lessons imparted are far from disposable, including the idea that life is too short to deny oneself treats or wear uncomfortable shoes. Those may be surface level messages, but the conversations about our choices in life — or death — are deep and resonant.

MPA rating: R (for language and brief drug use)

Running time: 1:29

How to watch: In theaters