The Untold Story (The Invisible Library, Bk. 8)

Irene is trying to learn the truth about Alberich-and the possibility that he's her father. But when the Library orders her to kill him, and then Alberich himself offers to sign a truce, she has to discover why he originally betrayed the Library.

With her allies endangered and her strongest loyalties under threat, she'll have to trace his past across multiple worlds and into the depths of mythology and folklore, to find the truth at the heart of the Library, and why the Library was first created.