Set in a fictional 19th century England, is the story of Allen Walker, a 15-year-old boy who roams the earth in search of . 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 . Lenalee is determined to confront a Level 4 Akuma that's out to kill Komui, but her only chance is to reclaim her Innocence and synchronize with it. The Level 4 is not inclined to wait around and pursues its mission even against the best efforts of Lavi and Kanda. It's left to Allen to hold the line, but it soon becomes obvious he has no hope of doing it all by himself!