In recent years, one horror film always seems to emerge early on as the best horror film of the year. In 2017 it was Jordan Peele’s Get Out; in 2016 it was Robert Eggers’ The Witch; in 2018 that honor goes to Ari Aster’s Hereditary. Starring Toni Collette as a woman struggling to cope with the increasingly disturbing implications of her mother’s death, Aster’s ferocious directorial debut plumbs the darkest depths of mental illness to reveal the true meaning of psychological terror.

When her elderly mother Ellen dies, Annie (Collette) feels somewhat relieved: Ellen struggled with DID (dissociative identity disorder) and kept many secrets over the course of a life fraught with tragedy; Annie’s brother was a schizophrenic who committed suicide when he was just a teenager. In her mind, Ellen’s death marks the end of a long family history of suffering and mental illness. Annie – an artist, wife and mother of two — is eager to put the past behind her.

But some things, as the title implies, aren’t easy to shake. Not long after Ellen’s death, Annie begins seeing apparitions while mysterious symbols pop up around her home. Her introverted daughter Charlie (Milly Shapiro) begins displaying increasingly strange behaviors, too. And then another tragedy strikes — one far more devastating than the last — that sends a grief-stricken Annie reeling down a spiral of exceedingly personal horror. Is she losing her tenuous grip on reality, or is there something more sinister lurking within her family’s ancestry?

With gorgeous, pointed cinematography, Aster stages Hereditary as the life-size version of Annie’s artwork: Vaguely disquieting miniature tableaus that depict everyday banalities with uncanny detail. Like these displays, Annie and her family appear trapped in a series of tableaus, in which anxieties lurk in the peripheral shadows and tensions mount to unbearable heights before giving way to their horrible, inevitable outcomes.

Collette, Shapiro, and Alex Wolff (as Annie’s burdened son, Peter) deliver remarkably soulful performances in a film that feels like a feature-length panic attack — punctuated with macabre imagery and horrific sequences that fully capture the feeling of a waking nightmare. Aster effectively — maybe too effectively — straddles the line between surrealism and reality, reflecting Annie and Peter’s exceedingly unsteady mental states.

Few films have explored the persistent, seemingly inescapable terror of mental illness with such alarming precision. Hereditary delivers the goods (and then some) when it comes to genuine scares and disturbing imagery, but its efficacy resides entirely in its cerebral preoccupations: Is mental illness a trait, passed down from one generation to the next like some devastating mantle? Is it a prescribed role waiting to be fulfilled? Or is it a performance derived from psychosomatic belief? Is Annie destined to become just like her mother, or has she merely convinced herself that this is her fate?

Aster spends the first hour or so of Hereditary absolutely luxuriating in existential dread, placing the weight of these questions firmly on the viewer’s chest. By the third act, that suffocating feeling gives way to a downright frightening finale, in which all the pieces of this traumatic puzzle come together in a distressing crescendo.

Hereditary is weighty horror that builds to an impossibly heavy finale, the metaphorical implications of which land on the heart like a ton of bricks. As with some of its indelibly disturbing imagery, this is not cinema for the faint of heart. But those who subject themselves to Ari Aster’s brutal psychological examination may find themselves rewarded by the experience — and with all the intimate devastation it conjures.