The exorcist's only work isn’t to exorcise possessed people or pure hunted places. They fight against monsters born from people's sins, called shadows. They use the power granted by God and some use the powers they discovered on their own.
The story follows two people. Saint of Sin, Theo Villeneuve, and his student Senzi. They arrive in Paris before Christmas comes to prepare the ritual that would exorcize all the newly born shadows. Theo felt that something dangerous was coming that night. He asked fellow exorcists to help him with that matter.
What is it that Theo, the strongest exorcist in Europe, worries about and needs the help of three other strong exorcists to assist him with the ritual? Can they stop the tragedy that could come this Christmas?