Thelma tells the story of a sheltered young woman who discovers she has an inexplicable power that materializes when she feels desire for a female student at her university.

[7][8] Thelma is a lonely and repressed young woman from an ultra-religious Christian family who has lived a sheltered life under the protection of her father, Trond, and disabled mother, Unni.

Once, when feeling neglected and jealous of the attention given to her younger sibling, and wishing him to be quiet and gone, she involuntarily caused him to teleport from his crib and reappear underneath the sofa.

Realising her utter distress, her parents tell her the truth, which is that she is somehow able to manifest whatever she deeply wants and that she inherited the same inexplicable ability from her grandmother (who blamed herself for the disappearance of Thelma's grandfather and was kept sedated in a psychiatric nursing home by Trond).

Earlier, while visiting Anja, Thelma recalled how her father once held her hand over a lit candle until it almost burned so that she could feel what Hell's eternal fire was like.

[19][20][21] It premiered in the United States at Fantastic Fest on 21 September,[22][23][24] and screened at the New York Film Festival as a Main Slate selection on 6 October.

The website's critics consensus reads, "Thelma plays with genre tropes in unexpected ways, delivering a thoughtfully twisty supernatural thriller with a lingering impact.

[42] In the Los Angeles Times, Justin Chang said the film was a "muted and moody supernatural chiller" that is "thoughtful and beautifully composed" with sequences "that tap into a vividly primal sense of terror".

[44] AfterEllen praised the performance by Harboe as "exhilarating, and incredibly moving", and said that "in a sea of lesbian films that are often repetitive, Thelma explores analytical territory that none other has before".

[46] Bilge Ebiri of The Village Voice described the film's story as moving "away from the monstrous, toward compassion and understanding ... prob[ing] the profound underlying sadness beneath tales of possession" and "makes vivid the protagonist's loneliness and despair".

[49] Andrew Barker of Variety described the film as "an unnervingly effective slow-burn, and those with the patience for Trier’s patient accumulation of detail will find it pays off in unexpected ways".