Although it comes from the filmmaking duo behind “Goodnight Mommy” and “The Lodge,” Veronika Franz and Severin Fiala‘s “The Devil’s Bath” is not a horror movie. Its sinister, woodsy atmospherics, where wet leaves mingle with mud and fishscales and menstrual blood, may suggest witchcraft or devil worship. But it is actually something far more frightening — an exploration, based on real records, of a chapter of Austrian history so dark it could be a black hole, which might account for its invisibility to posterity. But if the story is so pitilessly bleak you may want to look away, the filmmaking craft is so compelling that you can’t. The world of “The Devil’s Bath” is one that cannot be easily escaped, however much one might want, in the words of one of the women it emblematizes, “to be gone from it.”

With only a couple of feature acting credits to her name, Anja Plaschg (who as Soap&Skin also provides the soulful scraping strings and broken, breathy folk hymns on the soundtrack) is astonishingly convincing as Agnes, the young woman first seen happily weaving berries and twigs into her bridal headdress. It is 1750 in the Styria region of Upper Austria and Agnes is to marry Wolf (David Scheid) and move to his lakeside fishing community some way away from her native village.

The wedding is a joyful occasion, even if Agnes is nonplussed by the hillside house Wolf has borrowed money to buy for them. When her brother gives her the dismembered finger of a woman recently executed for infanticide (an act we witness in the film’s somber prologue) to use as a fertility token, she happily accepts, and places it under her and Wolf’s shared mattress. Religiosity and grisly, quasi-pagan superstition co-exist quite easily here.

However Wolf, who seems a little fixated on a good-looking male neighbor, does not consummate their marriage that night, nor the next. And Agnes is trying and failing to the learn the ropes of her new lifestyle of fishing and homemaking, and isn’t helped by the constant interfering supervision of her mother-in-law (Maria Hofstätter). Little cruelties mount up — Wolf unthinkingly discards Agnes’ precious little trove of papery butterfly and dragonfly wings. Agnes’ tiny act of rebellion in taking the skillets down from the hooks on which her mother-in-law insist they be hung is quickly reversed. Soon she finds herself spending more time alone, gazing at the wax doll of the infant Jesus at church, murmuring prayers and humming Marian hymns before the moldering corpse of the murderess, which has been left as a strange kind of shrine in the woods. Does Agnes pity the dead woman or envy her the end of all her troubles?

Franz and Fiala’s screenplay is gripping in its austerity, but it contains nothing in the way of surprise: once you understand the rapidly descending track this narrative is set upon, it continues plotting a viciously straight line from that brief dazzle of wedding-night hope down to previously unplumbed depths of despair without the slightest deviation. But Plaschg imbues the quiet Agnes with a riveting interiority, in an exceptional performance that exudes the same rough-hewn anguish that permeates every aspect of this immaculately fashioned production.

From the textures of Tanya Hausner’s costume design — scratchy hessian fabrics crudely cinched in with drawstrings — to the warp and weft of light and earth in Martin Gschlacht’s extraordinary photography, the world of “The Devil’s Bath” seems less filmed than it is woven out of the elements. In the odd moment of grace, like when a butterfly lands on Agnes’ upturned face, or the many gory acts of slaughter and execution, the imagery braids blood and beauty together as in a crown of thorns.

“The devil made me do it” is the frequent refrain of the piously insane. But here murder is motivated not by Satan, but by a loophole in ecclesiastical doctrine, which states that a murderer might attain forgiveness and die in God’s grace, where a suicide cannot, and must be damned. The premeditated logic of this “suicide by proxy” strategy makes dubious the suggestion of insanity or possession on the part of these killers for sure. But there is also the creepy idea that in a society this circumscribed and oppressive perhaps taking another’s life was one of the only truly free, independent acts that a woman could commit.

It is terrible to contemplate the 400 similar cases that a closing title informs us are recorded in the Austrian annals. But perhaps it’s even more so to imagine the many thousands more women who lived out their days exactly as they were meant to: in miserable servitude to their husbands, to their communities and to an uncaring God.