"Dantalian no Shoka" is a manga series set in a post-World War I era, blending elements of mystery, fantasy, and gothic aesthetics. The narrative centers around Huey, a young ex-soldier who inherits a mysterious library from his late grandfather. This library, known as the Bibliotheca Mystica de Dantalian, contains forbidden books called Phantom Books, which hold dangerous and supernatural powers. Alongside the library, Huey encounters Dalian, a girl with striking blue hair who serves as the "gatekeeper" of the Bibliotheca. Together, they embark on a journey to recover and seal away Phantom Books that have been misused or unleashed into the world.

Huey and Dalian form an unlikely partnership, with Huey acting as the keykeeper, capable of unlocking the library's secrets, while Dalian possesses the knowledge and power to control the Phantom Books. Their mission often brings them into conflict with individuals who seek to exploit the books for personal gain or destructive purposes. Each arc typically revolves around a specific Phantom Book, its unique abilities, and the consequences of its misuse. The stories explore themes of human desire, the corrupting influence of power, and the moral dilemmas surrounding knowledge and its control.

The series is episodic in structure, with each chapter or volume focusing on a self-contained story tied to a particular Phantom Book. However, overarching threads gradually reveal more about the origins of the Bibliotheca Mystica de Dantalian, Dalian's mysterious past, and the true nature of the Phantom Books. The dynamic between Huey and Dalian evolves over time, balancing moments of tension and camaraderie as they navigate the dangers of their mission.

The setting is richly atmospheric, drawing heavily from gothic and steampunk influences, with detailed depictions of early 20th-century Europe. The narrative maintains a consistent tone of intrigue and melancholy, underscored by the moral ambiguity of its characters and the consequences of their actions. Huey's pragmatic and often skeptical demeanor contrasts with Dalian's enigmatic and occasionally aloof personality, creating a compelling dynamic that drives the story forward. The series explores the duality of knowledge as both a tool for enlightenment and a source of destruction, weaving a complex tapestry of mystery and fantasy.