Her whole life, Ava (Alba Baptista) has had dreams in which she's dead. In the dreams, she rises up from her body and sees her lifeless form. She wakes up from her dream to discover she's in a strange place, and that she has superpowers. A priest who belongs to the Order of the Cruciform Sword explains to her that she is the new halo bearer.
However, when he learns that she's a nonbeliever, he wonders how their greatest weapon against evil wound up in her. She's introduced to a warrior nun, who tells her the halo is a gift, making her God's champion. The halo enhances whatever natural abilities she already possesses.