Ryusuke Hamaguchi’s first French-language film, “All of a Sudden,” is about caring for others, creating emotional bonds and what it means to truly see another person.

The immediacy implied in the film’s title is quietly ironic, given that it unfolds over three hours and 16 minutes, its dramatic weight accruing through long conversations, unhurried silences and the rhythms of daily life inside a Parisian care facility.

The story follows Marie-Lou Fontaine (Virginie Efira), the director of a care center on the outskirts of Paris who is waging a battle to introduce Humanitude, a French philosophy of caregiving that treats elderly residents with dementia as full human beings. When a chance encounter brings her into the orbit of Mari Morisaki (Tao Okamoto), a Japanese theater director with Stage 4 cancer who is in Paris for a production, the two women are drawn together by the same stubborn conviction that persevering in one’s beliefs can create real change.