The main character of the series is Allen Walker, a young Exorcist who recently joined the Black Order after training with his master General Cross Marian. When presenting himself to the organization, he is mistaken for an enemy and is attacked by another Exorcist, Yu Kanda. However, once the mistake is realized, Lenalee Lee prevents Kanda from causing further mishap. Once inside the headquarters, Allen learns he is the prophesied "Destroyer of Time" who is the only one who can defeat the Millennium Earl. As the series progresses, Allen meets many of the members of the Black Order headquarters as well as those in other branches worldwide. He eventually meets a young, aspiring bookman called Lavi and his predecessor Bookman, who follow Allen on his adventures to witness and record the event