Hugh and Dalian investigate cursed books that warp reality, but the real draw is watching them move through a perpetually gorgeous gothic world together. Every frame looks like it was painted by someone obsessed with shadows and candlelight. The episodic cases blur together, but the chemistry between them never does, their banter is sharper than whatever mystery they're solving that week.

Hugh Anthony Disward, called Huey, inherits his late grandfather's mansion and book collection, but only on the condition that he also becomes guardian of the Bibliotheca Mystica de Dantalian and looks after a mysterious girl named Dalian. The archive holds forbidden books of demonic origin, known as Gensho or Phantom Books, which threaten the balance of the world yet still draw people in with their taboo allure. Dalian turns out to be the gateway to that library herself. Together, Huey and Dalian take on cases involving these dangerous books and work to seal them away in a supernatural mystery with action elements.