Based loosely on a French film called “Duelles,” “Mothers’ Instinct” unfolds in a Hollywood version of ‘60s suburban America. In this place, everyone gets dressed up for even the most minor occasions. The women are always gorgeously fashioned, and the men wear ties. Delhomme’s film, from a script by Sarah Conradt, takes place almost entirely in the homes of two women: Alice (Jessica Chastain) and Celine (Anne Hathaway). In the film’s rushed opening scenes, we meet the husbands, Simon (Anders Danielsen Lie) and Damian (Josh Charles). There are hints of a little tension in both marriages, and it’s revealed that Celine and Damian struggled to have their only child, Max (Baylen D. Bielitz). While Max plays with Alice & Simon’s son Theo (Eamon O’Connell), we learn that the latter is allergic to peanuts in a narrative move that would accurately be called “Chekhov’s Cookie.” (You don’t reveal an allergy in a film this tightly plotted if it’s not coming back later.)

One day, Alice looks out her window and sees Max on the railing of the family’s third-floor balcony, trying to hang a birdhouse he made at school. She breaks into a full panic, trying to run through a shortcut between the two houses that the kids had made, but she’s unable to get there before Max falls to his death as his mom vacuums inside. Of course, both women go into full-blown grief spirals. Celine’s mental break comes from the unimaginable loss of a child, while Alice struggles with the question of whether she tried hard enough to get to Max before he fell. There’s a powerfully emotional film buried under the noir twists of this one, a movie about how people are forced to move on after something has shattered their entire lives. How could you even get through the day, much less look at your neighbor the same way again?

Alice starts to think that Celine is moving on in a manner that has earned the film comparisons to Hitchcock. Without spoiling, Max isn’t the last member of these families to die, and Alice is the only one who suspects that Celine’s grief has turned to vengeance. The midsection of “Mothers’ Instinct” is its strongest, one in which we’re forced to question if Celine has turned to violence or if these are all coincidences. Couldn’t it just be Alice’s guilt that has led her to suspect the worst? Hathaway and Chastain are truly excellent in this midsection, including one of my favorite line readings of the former’s career. With her work in the superior “Eileen” and now this, Hathaway is proving how much she would have been totally at home in a different era of Hollywood, and I’m here for it. Both performers sometimes lean into histrionics, but they’re well-modulated when the script calls for it, truly holding the film together with each of their interesting choices as actresses.