Are you ready for the year's scariest movie? I don't think you are, not at all.

With the independent horror feature "Hereditary," outsiders tight on budget but rich on talent have created an instant classic of visceral tension. The film is a nerve-jangling goose bumps delivery system more effective than any fright film a major studio has served up since "The Exorcist" or "Rosemary's Baby." It feels like a haunted house story from the vacant, quiet opening shots, but it is much, much more.

Ari Aster, who wrote and directed, stays close to classic craft, creating two hours of primal fear without mindless jump-jolts, possessed cellphones, slashers or phantoms caught on home security video. Aster, making his first feature-length film, knows that making us await the terrifying is more frightening than experiencing it. And when the fears do arrive, they are all the more excruciating because we have followed the ticking countdown to doom with growing woe.

This film focuses on a woman's psychic fixation on old emotional scars, digging deep into the fears that lurk below our consciousness from childhood until our final days. Technically subtle yet robust, the movie can turn a gloomy home corridor that feels a bit too long into a worry that will electrify the hairs on your neck. The interior cinematography is dim but not murky, the editing elegantly understated and the score unsettling without overdone, churning volume.

The less you know of the plot, the better, but here are some general facts: The movie centers on the Graham family, living on a comfortable private spread of the rural American West with many memories, few of them happy.

The couple came to parenthood somewhat late in their lives, largely because Annie (Toni Collette in an intensely physical performance) can barely deal with her own troubled childhood with a domineering, deeply difficult mother. Annie has become an artist of some renown, whose fastidious doll house miniatures reflect the handsome look and dark sensibility of her own residence. Her late mother lived there in failing health for years, and now remains an unwelcome trove of memories to Annie even after death.

Annie's kind, patient husband Steve (Gabriel Byrne) remains supportive of his wife's emotional rises and falls, hoping to maintain a tolerable life for their not-so-innocent children. The more typical of the two kids, a standard blend of solid student and pothead, is Peter (versatile Alex Wolff, outstanding as a Boston Marathon bomber in "Patriots Day" and a punk rock wiseguy in "The House of Tomorrow"). More problematic is 14-year-old daughter Charlie (Milly Shapiro, whose atypical looks are used to telling dramatic effect).

As we get to know the family, it becomes clear that each one is an oddball. Charlie, in her close-to-childlike state, feels less interest than the others in hiding the fact. Like her mother, she creates art to express her feelings, but it involves grotesque materials like decapitated birds' heads.

The sanest strange person in the uniformly superb cast is Joan, a woman who embraces Annie after a tragedy drives her further from the collapsing wreckage of her life. Ann Dowd, infinitely creepy in "The Handmaid's Tale," here is wholesome, caring and sensitive to Annie's bereavement, with a spiritual suggestion for her self-care, explaining that anyone can be a medium.

When spine-chilling shock tactics appear — and, lordy, do they appear — they bear unlimited, unexpected menace. There are horrifying spirits or ghosts or something here, though they may be produced by the characters' imaginations, terrible dreams or telepathy. Blurring the line between reality and fantasy doesn't weaken the film's richly ambiguous tone; it deepens it.

What seems disturbingly honest is the feature's intimations of grief, guilt, rejection and child pathology. Then, following an hour of everyday dread, it walks us unto the mouth of madness, and all bets are off. "Hereditary" shows what Jean-Paul Sartre really meant by "hell is other people."