A former Catholic priest named Menéndez finds himself released from prison and assigned to a new residence, grappling with the heavy burden of his past. His incarceration followed a traumatic incident during an exorcism that led to the tragic death of a boy. Plagued by guilt, Menéndez is frequently tormented by dreams featuring both the boy and his mother, Marisa, for whom he harbors complicated feelings. As Marisa visits him regularly, she proves to be a source of comfort, devoid of any blame towards him for her son's demise, often tidying up his home in a nurturing gesture.
Amidst his turmoil, a friend from prison, Sebas, reaches out for help, convinced that his daughter Raquel may be under demonic possession. Initially hesitant, Menéndez ultimately agrees to meet this rebellious young woman. Raquel vehemently denies her father's claims, indulging in taunts that provoke varying responses from the conflicted priest—half of him drawn to her audacity while the other recoils in disapproval. Throughout these encounters, Menéndez often converses on the phone with a mysterious caller, addressing them as if they are God, further challenging his wavering faith.
As he starts to believe in Raquel's possession, Menéndez invites Sebas to join him in a desperate attempt to perform an exorcism. Their methods quickly spiral into darkness as they resort to torturing Raquel to extract the demon's identity. When their efforts reach a breaking point, Sebas collapses into despair, embracing his daughter and apologizing for their actions, catalyzing the demon's dramatic manifestation. The creature overwhelms both men, binding them as it confronts a heartbroken Sebas.
In a frenzied turn of events, Menéndez escapes, and they manage to restrain Raquel once more. With heightened determination, the duo perseveres in their exorcism, successfully forcing the demon into a physical form. Menéndez discovers with horror that it mirrors the entity that once tormented Marisa's son. Utilizing a makeshift cross, he finally conquers the demonic force, which flees in defeat. As a grateful Sebas and Raquel depart, Menéndez, covered in blood, relays his triumph to the enigmatic caller. Yet, as the phone ominously reveals itself to be disconnected, a ghostly, nun-like figure glides toward a satisfied Menéndez, leaving his fate uncertain.
