Synopsis: Axlin and Xein’s paths once again cross, but both are farther than ever before. Axlin finds out that, in spite of the presence of the Guardians, the number of attacks have increased as of late within the walls of the Citadel, which in theory is the safest place in the world. On the other hand, while trying to help his friend Dex with a personal problem, she will become enmeshed in a conflict which involves several aristocratic families of the old city.
In turn, Xein discovers unmentionable monsters, dangerous creatures that live with the humans and that only the Guardians are capable of detecting. His loyalty with the Guardian forces him to keep the secret hidden from the rest of the people, and especially of Axlin, which will again put a new wall between them.
Nevertheless, the unmentionable monsters stalk her without her realizing it, for which reason Xein and Rox will try to protect her, without revealing the true nature of the danger that threatens her. In the process, Xein will discover the history of his origins, a knowledge which will have her reconsider all that she knows about her world and the very reason of her existence.