Thousands of years ago, there existed those gifted with the power of God. Their mission: to destroy the ominous evils that lurk in the darkness known as "Akuma." Led by the Milenium Earl, Akuma seek to destroy fragments of "Innocence," the only weapons capable of harming the Earl and his army and bring about the Great Flood from a hundred years ago.

To prevent this tragedy from happening, the Black Order was formed as an organization dedicated to fighting the Earl. They recruit Exorcists, those with the inherent ability to accomodate Innocence, to fight against the Akuma.

In the late 19th century, Allen Walker—a white-haired boy armed with Innocence that takes the form of his entire left arm and a cursed eye that can see Akuma—is sent to the Black Order. There, Allen meets various comrades from the Order—the mercurial Yuu Kanda, the kindhearted Lenalee Lee, and the cheerful yet mysterious Lavi. Despite their different personalities, they have one goal in mind: to bring salvation to the souls of Akuma and prevent the Earl from destroying the world.