Lord Hugh Anthony Disward, commonly known as Huey, lost his eccentric grandpa, Sir Wesley Disward, who was a well-known collector of rare books, six months ago. According to his grandfather's will, in order to inherit his manor and all inside it, he must accept guardianship over the Bibliotheca Mystica de Dantalian—an archive containing forbidden knowledge—as well as care for a strange girl named Dalian. An old enemy of Huey's grandpa arranges a meeting with him as he settles into the mansion. Dalian, who suspects the competitor is Wesley's murderer, goes along and finds that the murderer possesses a Phantom Book—a cursed tome that Wesley attempted to put away. Huey discovers the Bibliotheca when the book puts the two in jeopardy.