It’s been 10 years since Diego Luna directed his last movie, a gap in which the Mexican actor spent his time starring in the likes of “Andor” and “Narcos: Mexico.” But he didn’t return to directing in order to make a splash or come up with a high-octane return. Instead, “Ashes,” which premiered on Wednesday at the Cannes Film Festival, is a quiet character study that gets its power from understatement and its style from embracing silence and darkness. Luna returned to directing not to show off, but to make a few points about compassion and empathy. 

With the help of some sterling actors that include Adriana Paz and Anna Diaz, he takes a small story, tells it without much embellishment and lets the results speak to the state of a fractured and hardhearted world.

“Ashes” (aka “Ceniza en la boca” or “A Mouthful of Ash”) opens in a darkened bedroom in Mexico, with a young mother, Isabel (Paz) waking her 14-year-old daughter, Lucila, and telling her, “I have to leave. Take good care of your brother, will you?”

Through the bedroom window, Lucy watches her mother get in a cab and drive away, exiting her children’s lives for what we later learn will be eight years. The film, based on a 2022 novel by Brenda Navarro, isn’t specific about what has driven her away to Spain; it wants to explore rather than explain the life of the immigrant in a new setting where the promise of opportunity is often dashed, and on the repercussions for those left behind. 

Lucy and her brother, Diego, because they follow their mother to Madrid years later, fall in both camps. The film jumps ahead to Lucy in Madrid, working as a nanny for a demanding woman who gets pulled away when her brother Diego hurts other kids at school. She’s crazily overburdened, but Luna’s approach is stark and underplayed. He drops you into her life and leaves empathy as a viewer’s only alternative.

Like her mother, Lucy left Mexico in search of promise – but when she walks down the street and watches as a plush couch is being lifted by a crane to an upstairs flat, it’s clear that everything about this tableau is out of her reach. Luna jumps from one vignette to another, both in Madrid and when she subsequently leaves for Barcelona, and there’s precious little hope that Lucy is going to turn her life around from one of drudgery.

Sure, she sneaks out at night sometimes to go dancing with her boyfriend, but when a clearly troubled Diego shows up at her door in Barcelona, there’s little sense that the reunion will end happily.

Luna likes to frame the action through windows and at a distance, and by design, his pacing is slow and meandering. The musical score is minimal, but the sound design is not: When Lucy gets a call with the worst possible news about Diego, her screams mesh into the sound of a city that has grown more chaotic and deafening by the moment.

A sequence back in Mexico, where Lucy feels compelled to go, reunites her with family left behind but also plunges her into a world of violence where young girls are “taken” and nobody will say why or by whom. Military or paramilitary vehicles roam the streets during blackouts, and the idea that she could make a life here is no more sensible than the pipe dreams she entertained in Spain.

Luna lays out a life in little flashes, and Anna Diaz holds the screen as he does. “Ashes” is a quiet return to directing, but it’s unsettling and hard to shake.