If Evil never sleeps, it's because Sister Calvary is its worst nightmare!

Sister Justine, a nun in a Spanish monastery, secretly fights demons as Sister Calvary alongside her dog Natas. During a mission, she meets Salomon Saba, a Muslim exorcist. Despite their mutual mistrust, they join forces against a powerful demon. When Justine discovers a mysterious power within her – which could save or doom humanity – she must decide whether to conceal it or risk using it to fight the forces of evil.