Marnie (Susan Sarandon) is the irresistible force who, just before this movie starts, meets the immovable object: devastating grief in the loss of her husband. She does not have the vocabulary to process this loss. And so she tries to hold onto the person she was before. And she tries to convince everyone around her — and herself — that she’s fine. “The Meddler” begins with a brief monologue about how much she loves living in Los Angeles, where she has moved to be near her only daughter, Lori (Rose Byrne). “It’s like Disneyland!” she says cheerfully.

But she has trouble filling her days and finding a place to use her generous impulses. And so, as the title indicates, she meddles. She calls Lori many times a day, and when Lori does not answer, she comes over — with a bag of bagels. Lori, grieving in her own way for her father and for a breakup with a handsome actor, does not respond, and so Marnie turns her attention to anyone who comes along, from Lori’s friends to the guy at the Apple store genius bar. What she does not feel ready to do yet is to say goodbye to her husband by burying his ashes and putting up a headstone in the family plot back in New Jersey. “It’s been a year,” she tells his brothers. But it has been two. And she is not ready to think about loving someone new, even after she meets a man who is from her home town and seems perfect for her (Michael McKean).

When Lori’s friend Jillian (SNL’s Cecily Strong) mentions that she needs a babysitter, and so Marnie shows up at her house — with bagels. Jillian says that she does not have a mother and she never had the dream wedding she wished for. So Marnie offers to give her a wedding. And when she encourages the Apple genius (Jerrod Carmichael of “The Carmichael Show”) to go back to school, she offers to drive him. She has so much to give, but the loss of her husband has left her with no place to give it and a fear of losing him even more if she changes too much or gets too close to someone else.

Sarandon gives one of her best performances, which means she is truly superb, and Byrne is excellent as well. When Lori’s ex and his new girlfriend find Marnie and Lori having dinner together on Valentine’s Day, there is a beautifully funny and heart-wrenching moment as both mother and daughter try so hard to appear to be doing fine that they do not notice they are undermining each other. In another scene of piercing bittersweetness, a day of emotional upheaval ends in mingled laughter and tears. JK Simmons brings dry wit and humanity to the role of an ex-cop and hen farmer whose quiet understanding gives Marnie her first chance to let go a little, and to acknowledge, after some resistance, that it is something she wants and needs to do, for herself and for Lori.

Writer/director Lorene Scafaria (“Nick and Nora’s Infinite Playlist” and “Seeking a Friend for the End of the World”) has a rare gift for finding the space in between joy and grief, and a rare understanding of the power of small moments to tell a big story. As Marnie watches Lori’s script being filmed, she is moved by the way Lori has used her writing to work through her grief, and as we watch this film, we share that feeling.

Parents should know that this film has some strong language, sexual references, and drug use.

Family discussion: Why does Marnie want to help people she hardly knows? What’s the difference between being supportive and meddling and how does that change in different circumstances?

If you like this, try: “Hello, My Name is Doris” and “Seeking a Friend for the End of the World”