One definition of great cinematography is pretty pictures that move. On that score, “A Long Winter,” the majestically moody new drama written and directed by Andrew Haigh (“All of Us Strangers”), more than qualifies. It’s set on a remote farm nestled high in the Rocky Mountains in the early 1950s, and the images — of jutting peaks and plunging valleys, of endless stretches of pine, of the craggy frosted grandeur of it all — are vivid enough to carry you away.

Yet the real definition of great cinematography is when a filmmaker, working with a bold camera artist (in this case, André Turpin), frames the images so they don’t just dazzle but lure the audience, unfolding the action with a shimmering inquiry and suspense, as if each shot were another sentence in the story it’s telling. That’s the way “A Long Winter” works. Based on a novella by Colm Tóibín, it’s a film austere enough to risk alienating its audience, yet once you get onto its wavelength you stay right there, inside the movie’s world.

For a while, “A Long Winter” is so authentically homespun that you may feel primed for a kind of art-house Laura Ingalls Wilder experience. In a stately, creaky mountainside farmhouse, Mikey (Fred Hechinger) and Tom (Kit Connor) are adult brothers who sleep in beds right next to each other. They have a caring and respectful relationship that feels pre-media enough to seem downright exotic. But Tom is impatient with their sedentary lives, raising chickens and rabbits (which they sell for their pelts). He’s about to leave for Army service in Korea. Mikey, by contrast, says he loves this life — the tranquility of it, which he finds comforting. He left for a while too (to go to Idaho), but ultimately came back. As the two have dinner with their parents, the taciturn Lester (Ebon Moss-Bachrach) and the radiant Louise (Caitríona Balfe), the movie shows us what it’s like to feel protected by an old-world American family coziness.

It’s soon apparent, though, that there are dark clouds adrift in this clan. Loise, vibrant but tense, gets through her days by drinking wine. She tries to hide the extent of it, but Mikey — the last one in the family to know — has now figured it out. Early on, he and his folks pile into their ancient wood-sided Ford station wagon, riding down the mountain to the small town nearby, in order to purchase supplies. The town looks depressed (there’s a condemned movie theater that still has “The Snake Pit,” from 1948, on its marquee), but there’s a life to it, and Mike observes his mother having an afternoon drink and then lying about it.

It’s the deception, of course, that’s the red flag. Lester has always known about her drinking, but the moment has come (not the first) when he decides to intervene. Back home, after a heating-oil delivery (which is also a wine delivery), he throws out all of Louise’s cheap rotgut wine. He has decided, with a puritanical insistence, that he’s going to heal her by making her quit the booze cold turkey. But she’s having none of that; she feels like she needs the drink to survive. Caitríona Balfe acts with the impacted fervor of someone who’s caught in a life she chose but no longer wants. She’s trapped. And so, without her crutch, she leaves — just like that. As the first winter storm is coming. Is she seeking alcohol or death? Maybe both.

With Louise suddenly out of the picture, we may think that the movie has lost its most interesting character. And maybe it has. “A Long Winter,” set over the following three snowbound months, turns into a family drama of morose and foreboding mystery. Mikey adores his mother, problematic though she is. His father, on the other hand, is a piece of work. Ebon Moss-Bachrach seems to have been put on earth to play men who are total pills, and here he gives us the scowling, mustached, man-of-few-words frontier version. Lester and Mikey, engaging the local police, along with some relatives, begin the process of searching for Louise, but she has vanished with such eerie completeness that for a while I thought “A Long Winter” might turn out to be a ghost story — one that starts with an hour of realistic exposition.

There’s nothing supernatural about the movie. In a way, though, it is a ghost story. Louise — the presence of her absence — hovers over the wintry landscapes like a figment of loss and guilt. Her story, we realize, is tragic, but part of what makes it wounding is that the movie doesn’t demonize. Moss-Bachrach’s Lester, who originally came from New York City, is a stern taskmaster who wanted to be a farmer and wooed Louise over from the other side of the mountain; he thought the life they’d lead would be magical. But she grew disenchanted with it; she began to yearn for the middle-class life she saw in her Cosmopolitan magazines. And he couldn’t handle the disappointment of her unhappiness. So he clamped down. And she drank up. The movie fills in the backstory of this slow-motion trauma in a way that feels wrenchingly lifelike. Only it’s Mikey who now bears the burden of it.

“A Long Winter” is somber and placid yet told with such quiet confidence that it gets its hooks in you. The film is really about how Mikey discovers his inner life. An early scene, in which he makes eye contact with a young cop in town, is the tip-off — that Mikey is attracted to men. And what’s dramatic about this is that having grown up on a remote mountain farm in the 1940s, away from almost any remnant of civilization, Mikey has zero context for his erotic yearnings. He’s not even spooked by them (as we might expect him to be). Instead, Andrew Haigh, who has made such potent dramas of queer life (starting with “Weekend”), uses this story to craft the rare portrait of gay consciousness that feels rooted in an Edenic innocence. As Mikey, Fred Hechinger gives off young Tobey Maguire vibes, and the movie uses that aura with compelling poignance.

Louise, in all her flaws, was Mikey’s link to love. Now his link to love is that young officer, and the pictures he sees in his mother’s magazines, and the young man who comes to live with them as a cook and housekeeper — Jimmy (D’Pharaoh Woon-A-Tai), a biracial Native American, who is stoic and solemn enough to suggest a Kenneth Anger fever dream. You could say that there’s a “Brokeback” feeling to it all, with homoeroticism suffusing a period piece set before those feelings had been allowed into the culture. But “Brokeback Mountain” was a fully realized love story. “A Long Winter” is never consummated in that way. As the winter fades, and the vultures come, the movie points to something else: how a mother’s end could be the bridge to her son’s beginning.