Theresa (Kirsten Dunst) is lost, her pit of despair so deep and enveloping it's as if she has returned to that summer during her childhood when she briefly went missing among the California Redwoods. "When they found me," she says in opening voiceover, "I almost didn't want to come back." The dreamily provocative writing-directing debut of fashion designer sisters Kate Mulleavy and Laura Mulleavy, "Woodshock" is a forlorn tone poem with a fresh artistic eye unlike any other. When the works of so many filmmakers can be compared to past auteurs, the Mulleavy duo have crafted a singular work of understated, tormenting beauty.

The source of Theresa's grief appears to stem not only from the loss of her terminally ill mother (Susan Traylor), but from the circumstances surrounding her death (in grave pain, she had asked her daughter to help her end her life with a poison-laced spliff). Theresa, who has abided her mom's wishes and moved with boyfriend Nick (Joe Cole) into the house she has left behind, is reminded everywhere she turns of the loved one no longer there. She receives no respite from her job at a medical marijuana dispensary, either; it is here where she and boss Keith (Pilou Asbaek) devised the deadly concoction which took away her mother's suffering. Theresa, however, is suffering plenty, and this forest of mental anguish grows nearly insurmountable after she makes a fatal error at work.

A hypnotic depiction of one woman's battle with guilt and depression, "Woodshock" might best be described as a cinematic cousin to Charlotte Perkins Gilman's famed 1892 short story of mental illness, "The Yellow Wallpaper." The aura of sadness Kate Mulleavy and Laura Mulleavy bring to their and cinematographer Peter Flinckenberg's images is as indelible as it is lonesome, the pangs and mortality of real life overshadowing Theresa's idyllic memories of a woodland fairy tale existing right outside her door. All-too-fitting songs also sneak their way into the fabric of the story, the most memorable of them Suicide's "Dream Baby Dream" in a late scene at a bar.

The film's narrative minimalism leaves a few undernourished threads in its wake, none more so than Theresa's relationship with boyfriend—or is he her husband?—Nick, a lumberyard worker whom the viewer can never get a grip on. He is gone for long stretches and appears frustratingly slow to catch on that his partner needs serious help (that he doesn't bat an eye to nothing being in the fridge but an old, barely-eaten birthday cake is also questionable). The fight in him ultimately comes too late, with little reward or explanation. Perhaps that, then, is the whole point. Theresa has acquaintances in her life—among them, the waveringly sympathetic Keith and sweet teenage neighborhood boy Johnny (Jack Kilmer)—but no one who will take the first step in shining a light on Theresa's affliction.

In the portentously alluring "Woodshock," Theresa is trapped—within her own mind, within a life she doesn't want, in a place where the Redwoods around her signify a freedom for which she pines (it cannot be by accident that Nick's job is to cut down, thereby ostensibly killing, trees). Kirsten Dunst (2017's "The Beguiled"), who previously essayed a similarly haunted character in Lar Von Trier's 2011 study in apocalyptic depression "Melancholia," is strikingly, achingly believable, her pain emanating so deeply from within it might as well be sounding a death rattle. This could not have been an easy role—she is in nearly every scene, often in close-up, and must delve into a wave of despairing emotions—but the reward is seared to film. As Theresa arrives at the cusp of no return, rustic hallucinations threaten to overtake her, moving closer, becoming stronger. Pretty soon, they may just overtake her. "Woodshock" is ethereal and harrowing in equal measure, an unusual journey unforgettably at one with itself.