Menéndez is a retired priest who lives in seclusion from the world in his dark and dilapidated apartment. He suffers a crisis of faith, and is haunted by horrible nightmares and memories of past acts that torture him. One day he receives a visit from Sebastián, an old friend who is familiar with his past work. Sebastián claims that his daughter is possessed by a demon and begs for the priest's help to exorcise her, although he's well aware of the aggressive methods that Menéndez uses. Driven by Sebastián's insistence, as well as his own inner conflict, Menéndez takes the case as his chance for redemption. He has a new goal in life, but... is the girl really possessed?