The fifth installment in the Old Kingdom series by Garth Nix, which is among the top bestsellers of the New York Times. Lirael is no longer a shy Second Assistant Librarian. She is the Abhorsen-in-Waiting, ready to battle dead beings and bind Free Magic entities. She is also a Remembrancer and a user of the Dark Mirror.

When Lirael finds Nicholas Sayre lying unconscious after an attack by a hideous Free Magic creature, she uses her powers to save him. However, Nicholas is severely tainted by Free Magic, and Lirael must seek help for him at her childhood home, the Clayr's Glacier.

But as she returns to the Clayr, a messenger attempts to reach Lirael with a dire warning from her mother, Ariel, who has been dead for a long time, about the Faceless Mage. But who is the Mage and what are her plans? Once again, a great threat endangers the Old Kingdom and must be repelled not only in the living world but also in the cold, unyielding River of Death.