They call Montana “Big Sky Country” which I’ve always found to be the most beautiful nickname. It doesn’t quite make sense – how could the sky be bigger there than in London or Paris or Asbury Park, New Jersey? – but somehow an image still develops in the mind. Those snowy mountaintops and unobstructed horizons get plenty of screen time in Wildlife, a small gem of a film directed by Paul Dano, adapted by him and Zoe Kazan from a Richard Ford novel.

It is a quiet, subtle story and, as is so often the case when an actor takes their first trip behind the camera, a showcase for terrific performances. Front and center here is Carey Mulligan as a young wife and mother in 1960 edging toward independence. Jeanette (Mulligan) and Jerry (Jake Gyllenhaal) are new to this area of Montana, and may soon have to move again since Jerry’s lost his job as a helper at the golf club. Jerry is the guy who just keeps messing up. He’s too friendly, too chatty, too eager to ignore rules and too quick to get vindictive when things don’t go his way. With them in their rented house is their sweet and observant teen son Joe, played by Ed Oxenbould. It’s the type of character Dano himself would play when he was younger: a little awkward, but obviously wise.

Considering Joe’s intellect, there’s no point in hiding that Jeanette and Jerry are having marital problems. An early scene of Jeanette helping Jerry lick his wounds after getting fired is a remarkable trick. She has to seem believable enough to Jerry, but still make it clear to us that she’s silently screaming on the inside. Embarrassed at his prospects (and the fact that Jeanette has taken up work at a swim instructor) Jerry joins up with “the deadbeats” who ride off to try and contain the ever-burning wild fires. He’ll be back with the chill of the first snowfall, but until then the conflagration continues. It’s all very symbolic, but Dano’s style is to focus on detail and precision. (Joe’s apprenticeship as a portrait photographer aids with this.) The natural landscapepops off the screen, offering Wildlife a remarkably lived-in quality.

If there’s anything shocking in this film it’s how frank Jeanette is with Joe about her boredom and her desire to strike out and find a new relationship. There are hairstyle changes and provocative outfits (“this is my desperation dress”), and eventually the town’s divorced, wealthy owner of a car dealership (Bill Camp) starts hanging around. These scenes (including a boozy dinner party) teeter between funny, awkward and sad. Joe clearly understands what’s going on, but doesn’t know if he should relax and be friendly, or fight on behalf of his father. It’s clear he’s never angry at his mother, but his mind is always scrambling for a way to patch the family back together again.

What’s striking is how we’re left rooting for both of them. Oxenbould wears the sadness of a wounded animal on his just-about-mature face but, as Jeanette blossoms into a flirtatious woman, Mulligan plays her as if her feet can hardly touch the ground. It’s a very technical performance, lots of glimpses and witty lines thrown away in a lower vocal register. There are no shortage of laughs in Wildlife, but this is a fundamentally melancholy picture. It’s also an assured first film from an actor who will hopefully continue to direct.