Just like the lives of its characters, Infinitely Polar Bear is a triumphant balancing act. It’s a period piece that feels utterly contemporary. It handles issues such as living with mental illness, mixed-race families, and female breadwinners, but in the context of the film, these aren’t “issues,” they’re simply the facts of life for the family in writer/director Maya Forbes’ autobiographical story. And best of all, despite the potential for heavy-handedness, the film is told with grace and humor; it’s a fun film with a serious heart.

Taking place in Cambridge, MA in the later 1970s, Infinitely Polar Bear tells the story of the Stuart family. Cam (Mark Ruffalo), comes from New England old money, but his grandmother has a iron grip on the purse strings, so when he has a nervous breakdown and loses his job, it puts him, his wife Maggie (Zoe Saldana), and two elementary aged daughters in financial straits. Maggie moves the children from the Massachusetts country to a small apartment in Boston, where they scrape by in less than ideal circumstances. Once Cam is released and gradually improving, Maggie is accepted into Columbia’s MBA program and she proposes that Cam take care of Amelia and Faith in Boston while she studies in New York to eventually provide for the family, visiting on weekends.

Forbes and Saldana excellently portray how difficult a decision this is for Maggie; she loves Cam and knows that the responsibility could either stabilize him or sink him, but most of all she loves her daughters and wants what’s best for them long-term. Once Maggie leaves for New York, the bulk of the film shows Cam taking care of Amelia and Faith in Cambridge. Cam is a deeply loving, but deeply flawed father. He’s full of semi-practical talents, like making perfect crepes or identifying plants, but is sketchier on the more important things like getting the girls to school and cleaning house. At his best, Cam is spontaneous and fun, but there’s a razor’s edge between that and dangerous manic behavior, which both the girls and the audience can feel with an intuitive dread. There’s an excellent sense of lived-in detail throughout the film, from Cam’s elaborate hobbies that fill the apartment to the developing attitudes of the girls.

Mark Ruffalo, often excellent in supporting roles, is wonderful as Cam, creating a complex, flawed, yet endearing man and it’s also rewarding to see Saldana out of alien make-up and playing a very human role. Infinitely Polar Bear uses a light, but intelligent touch in dealing with larger, societal forces affecting the family. Maggie faces difficulty finding a job both as a black woman and as a mother, while others view Cam’s domesticity warily. Over-educated and living in genteel poverty, Cam has a healthy disdain for many of the more practical aspects of life, but Maggie subtly reminds him that this is a privilege of his background that she and many others don’t have. Infinitely Polar Bear is an impressive debut that finds drama and humor in the everyday minutia of a family in a non-everyday situation; Forbes has taken an immensely personal story and made it feel universal, an enviable skill for any filmmaker.