Suspicion is like a malignant tumour.
Addressed quickly, it can be excised with clinical precision by common sense and logical reasoning, leaving behind emotional scars that will heal over time; left untreated, the suspicion swells and steadily infects clear rational thought, poisoning loved ones against each other.
Set in 17th-century New England, The Witch is a slow-burning thriller about a fervently religious family torn asunder by the belief that their teenage daughter is in league with the Devil.
Writer-director Robert Eggers delivers a stylish and ambitious debut of remarkable clarity and emotional power that burrows under our skin and leaves us scratching helplessly in the dark, at the mercy of his dark and unsettling parable.
He steadfastly avoids the jump shocks and scares that have become emblematic of the modern horror genre.
The eponymous hag doesn't materialise unexpectedly out of the darkness, accompanied by a burst of staccato strings, characters don't abandon their senses and stumble blindly to their doom.
Instead, Eggers cranks up suspense until we are whimpering for mercy, underscoring our discomfort with a chilling orchestral score composed by Mark Korven.
William (Ralph Ineson) stands accused of "prideful conceit" before other members of his Puritan Christian community.
Unbowed and unmoved, he is excommunicated with his wife Katherine (Kate Dickie), eldest daughter Thomasin (Anya Taylor-Joy), son Caleb (Harvey Scrimshaw) and the twins Mercy (Ellie Grainger) and Jonas (Lucas Dawson).
The family travels by rickety cart to a clearing and establishes a new homestead and plants crops in time for the birth of a son, Samuel.
A witch (Bathsheba Garnett), who lives in the nearby forest, steals the baby during a game of peekaboo with Thomasin and uses the child's freshly spilt blood to restore her youthful lustre.
Katherine is devastated and William struggles to hold together his family as grief and guilt corrupt their love.
"We will conquer this wilderness. It will not consume us," he growls.
Poor Katherine's faith wavers - "Since Sam disappeared, I cannot see Christ's help as near" - and the conspiratorial twins accuse Thomasin of witchcraft, based on whispered conversations with the family's prized goat.
Matters come to a head when Caleb secretly ventures into the forest, gun in hand, and stumbles upon a moss-thatched cottage...
The Witch begins as a coming of age story, focusing on Thomasin's awkward transition to adulthood.
Once Samuel vanishes, nerves jangle and Eggers confidently unpicks the seams of the family's existence, eliciting a spellbinding lead performance from Taylor-Joy as the virginal teen, whose sexual awakening doesn't go unnoticed by her hormone-addled brother.
The script evokes the period in both dialogue and design, and cinematographer Jarin Blaschke uses lighting to stunning effect to suggest unspeakable horrors lurking just out of our field of vision.
As much as we want to look away, we're riveted to the spot.