In a brutal medieval world where innocence means life and guilt means death, Aron, captain of the castle guard, enforces order within the fortress. But when demons begin to corrupt men's hearts, violent events erupt, including repeated attempts to assassinate the lady of the castle. As Aron hunts the culprits, he encounters a demon that marks him, granting incredible strength but tainting his body with dark magic. Now, with his mind clouded and powers growing, Aron must unravel the mystery before the castle and his soul fall to ruin. (Source: Webtoon Entertainment)