In the quaint town of Tarascon, France, back in 1956, Father Noiret and young Jacques went about their daily duties in their church. However, their routine was shattered when Noiret was inexplicably lifted into the air, set ablaze, and met a horrifying end before the eyes of a terrified Jacques, who fled in fear.
Fast forward four years, Sister Irene finds herself in a convent in Italy, and Maurice is working at a boarding school in France. Irene, now serving the church, is haunted by a vision of Maurice pleading for help. Dispatched by the Cardinal, she teams up with Sister Debra, a novice struggling to accept miracles. Together, they embark on an investigation into a series of mysterious deaths across Europe attributed to the demon Valak.
Their journey takes them to Tarascon, where Irene is tormented by haunting visions. Sister Debra reveals a connection to Noiret's rosary, received from Jacques. Meanwhile, a delivery girl witnesses Valak communicating with a possessed Maurice before meeting a grim fate.
In Tarascon, Irene discovers that Valak is targeting descendants of St. Lucy, seeking a powerful relic associated with her. The trail leads to a former monastery, now a winery and boarding school. As they delve into the school's history, Irene and Debra uncover the dark secrets behind Valak's malevolent agenda.
At the boarding school, Irene and Debra confront a fully possessed Maurice. Sophie, a young Irish student, reveals a chilling legend about a stained-glass goat in the chapel linked to demonic occurrences. Using the goat's eyes as a guide, they unearth the relic and face a demonic manifestation.
Amid chaos and demonic attacks on students, Irene battles Maurice, who is under Valak's influence. The climax unfolds with a collapsing bell tower and a revelation about Irene's lineage. In a desperate moment, Irene and Debra use the relic to banish Valak, invoking the power associated with St. Lucy.
The next morning brings relief as Irene, Debra, and Maurice emerge from the ordeal. However, Irene harbors concerns as she watches Maurice join Sophie and her mother, Kate. The lingering question of what lies ahead adds a touch of uncertainty to the aftermath of their supernatural encounter.
