Principles of Angels (Hidden Empire)

While it is the first book in the Hidden Empire series, Principles of Angels introduces the world and characters in a way that allows new readers to start here without prior knowledge of the author's other works. The overarching narrative builds across the series, but this installment provides a complete story arc for its central conflict.

The primary storyline within Principles of Angels reaches a satisfying conclusion, resolving the immediate threats and mysteries Ciel faces. However, it also lays groundwork for future developments and leaves some broader questions open for exploration in subsequent books.