Three months after the events of Dark Heroism, things seem to go back to normal for Ladybug and Cat Noir, for the most part. But as a mysterious new threat appears, old wounds are reopened, leading to a chain of catastrophic events that will push our heroes to the very limit, and threaten the city of Paris as they know it.

Ladybug and Cat Noir have taken on many Akumatized villains, as well as meeting new heroes along the way. But when a new hero arises, he is nothing like what they've seen before. Now, they must help this new hero through his brutal methods, and vengeful motivation to keep their city safe from this troubled hero, and the threat he brings with him.