Sister Maria, a young nun living in a secluded convent nestled deep in the Romanian wilderness, shocks her fellow sisters when she claims to have been impregnated by God himself. Knowing immaculate conception goes against Catholic doctrine, the head Abbess alerts the local priest, Father Nikolai. He is deeply disturbed by Maria’s claim, which seems to align with an ancient Romanian prophecy about the birth of twin boys – one the Messiah who will save humanity, the other the Anti-Christ destined to destroy it.
Word reaches the Vatican quickly. The prophecy is familiar to them, though they had long considered it mere superstition. Nevertheless, they summon Father Damien, a specialist in religious mysteries, to lead a team of priests including Brother Gabriel and Brother Lucas to the remote convent to investigate.
Upon arriving at the snow-covered convent, the priests immediately sense a potent, dark force surrounding the area. Maria, now visibly pregnant, greets them calmly, insisting her conception was divinely inspired. As the team begins evaluating Maria’s claims, they encounter escalating supernatural events – bleeding walls, disembodied whispers, ominous ancient Romanian symbols appearing throughout the convent.
Brother Gabriel becomes convinced Maria has been possessed by a demon who raped her, spawning the Anti-Christ. Father Damien remains skeptical, believing they must thoroughly test Maria for true holiness before making judgments. Meanwhile, Brother Lucas develops a attachment to her, insisting she is untouched by evil.
Seeking answers, Father Damien finds books on Romanian occultism hidden away in the church rectory, left behind by a priest long ago who had researched the prophecy. The texts describe rituals for conjuring both benevolent and malevolent spirits. Damien keeps his discovery secret, burnt talismans found with the books making him suspicious about the convent’s history.
When Maria goes into sudden labor, she is sequestered in her quarters with Damien and Lucas attending her. After an unnaturally long and agonizing delivery, twin boys are born – both with unusual markings but otherwise normal. The priests await signs of which infant might be the prophesized Messiah or Anti-Christ.
Maria refuses to relinquish the babies, certain of their pure divine nature. her behavior becomes increasingly erratic. When one boy develops a mysterious illness, Gabriel becomes convinced he is the evil child and attempts to kill him in secret. Damien stops him, admonishing that they still do not have conclusive proof.
The tensions finally erupt into chaos when Lucas professes his love for Maria and vows to protect her and the twins. As the monks clash violently over the fates of the children, Damien must fight his own doubts, torn between faith and reason. A terrifying entity haunts the rectory, disturbingly drawn to the ailing twin.
Is one child meant to guide humanity to salvation while the other brings about its destruction? Or has some darker power manipulated them all toward its own sinister ends? The truth has become obscured, even to Damien, their beliefs pushed to the brink as they desperately seek to deliver the world from evil.