The spectacular landscapes of Montana (and its stand-in New Zealand) are vast horizons with distant escarpments under a broad sky that dwarfs the people and animals beneath it. For all that, this is a claustrophobic and intimate story about the entwined lives of two brothers, Phil and George Burbank, who are so close they still sleep in the same room but whose personalities could not be further apart.

Phil (Benedict Cumberbatch) is the hyper-masculine rancher in furred chaps that give him a bestial air; he is classically educated but prefers to emphasise his manhood through macho displays and casual cruelty. Fatso, he calls George (Jesse Plemons), who is quiet, respectful and observant and who at a dinner in town meets the café owner Rose (Kirsten Dunst).

Even though Phil terrorised Rose and her son – the effeminate Peter (Kodi Smit-McPhee), whose hand-made paper flowers Phil used to light a cigar – George returns to court her. It is the first rift between the brothers as George brings Rose home to the ranch and marries her.

This is Jane Campion’s first film in 12 years, and we are right to expect something dark and unnerving, poetic and sexual. It is almost 30 years since The Piano, with its searing story of a mute woman whose jealous husband hacks off a finger, denying her the music she loved, and setting the tone for Campion’s work.

Halfway into this story, based on the book by Thomas Savage, it is impossible to know where it is heading as Rose quietly succumbs to Phil’s torment. In another room he picks out a tune on his banjo while she struggles to play it on the piano that George bought her, thinking it would make her happy.

Peter keeps his distance and goes away to start medical school but returns one holiday, where he does his best to stay out of Phil’s way.

The film builds imperceptibly towards a quietly Gothic climax you are barely aware is happening as their essential natures are revealed. Smit-McPhee’s withheld performance as an unusual young man accustomed to mockery accounts for much of the film’s success, as does Cumberbatch as the sinister cowboy with secrets who idolises the now dead “Bronco” Henry, a fellow rancher who taught him everything he knows.

No wonder everyone wants to work with Campion; she has the ability to extract unforgettable performances from even the best actors.

The Power of the Dog is on Netflix now. It is also currently screening at Palace Nova cinemas in Adelaide.