Set in a fictional 19th century England, D.Gray-man is the story of Allen Walker, a 15-year-old boy who roams the earth in search of Innocence. Washed away to unknown parts of the world after The Great Flood, Innocence is the mysterious substance used to create weapons that obliterate demons known as akuma.

A Noah called Lulu Bell leads an army of Akuma against the exorcists in order to retrieve the Egg, a device that will enable the Millennium Earl to activate his new Ark. With most of the surviving exorcists incapacitated, it's up to Allen and Bookman to try to stop the Akuma from taking off with the Egg. But when the Akuma try to make off with Allen as well, all Hell really breaks loose!