The Mexican writer-director Michel Franco is something of a feel-bad filmmaker. His style can be chilly and severe. His characters are often comfortable bourgeois types who are in for some class-based comeuppance. His usual method is to set up the camera at a distance from his characters and watch them squirm in tense, unbroken long takes.

Sometimes all hell breaks loose, as in Franco's dystopian drama New Order, about a mass revolt in Mexico City. Sometimes the nightmare takes hold more quietly, like in Sundown, his recent slow-burn thriller about a vacation gone wrong.

I haven't always been a fan of Franco's work, not because I object to pessimistic worldviews in art, but because his shock tactics have sometimes felt cheap and derivative, borrowed from other filmmakers. But his new English-language movie, Memory, is something of a surprise. For starters, it's fascinating to see how well-known American actors like Jessica Chastain and Peter Sarsgaard adapt to his more detached style of filmmaking. And while his touch is as clinical and somber as ever, there's a sense of tenderness and even optimism here that feels new to his work.

Chastain plays Sylvia, a single mom who works at an adult daycare center. From the moment we meet her, at an AA meeting where people congratulate her on her many years of sobriety, it's clear that she's been through a lot. She's intensely protective of her teenage daughter, rarely letting her hang out with other kids, especially boys. Whenever she returns home to her Brooklyn apartment, she immediately locks the door behind her and sets the home security system. Even when Sylvia's doing nothing, we see the tension in her body, as if she were steeling herself against the next blow.

One night, while attending her high school reunion, Sylvia is approached by a man named Saul, played by Sarsgaard. He says nothing, but his silent attentiveness unnerves Sylvia, especially when he follows her home and spends the night camped outside her apartment. The next morning, Sylvia learns more about Saul that might help explain his disturbing behavior: He has early-onset dementia and suffers regular short-term memory loss.

Some of the backstory in Memory is confusing by design. Sylvia remembers being sexually abused by a 17-year-old student named Ben when she was 12, and she initially accuses Saul of having abused her too. We soon learn that he couldn't have, because they were at school at different times. It would seem that Sylvia's own memory, clouded by personal pain, isn't entirely reliable either.

Despite the awkwardness and tension of these early encounters, Sylvia and Saul are clearly drawn to each other. Seeing how well Saul responds to Sylvia's company, his family offers her a part-time job looking after him during the day. As their connection deepens, they realize how much they have in common. Both Sylvia and Saul feel like outcasts. Both, too, have issues with their families; Saul's brother, played by Josh Charles, treats him like a nuisance and a child. And while Sylvia is close to her younger sister, nicely played by Merritt Wever, she's been estranged for years from their mother, who refuses to believe her allegations of sexual abuse.

The movie poignantly suggests that Sylvia and Saul are two very different people who, by chance, have come into each other's lives at just the right moment. At the same time, the story does come uncomfortably close to romanticizing dementia, as if Saul's air of friendly, unthreatening bafflement somehow made him the perfect boyfriend.

But while I have some reservations about how the movie addresses trauma and illness, this is one case where Franco's restraint actually works: There's something admirably evenhanded about how he observes these characters trying to navigate uncharted waters in real time. Chastain and Sarsgaard are very moving here; it's touching to see how the battle-hardened Sylvia responds to Saul's gentle spirit, and how he warms to her patience and attention.

This isn't the first time Franco has focused on the act of caregiving; more than once I was reminded of his 2015 drama, Chronic, which starred Tim Roth as a palliative care worker. I didn't love that movie, either, but it had some of the same unsettling intimacy and emotional force as Memory. It's enough to make me want to revisit some of Franco's work, with newly appreciative eyes.