In this fifth book, Ulysses and Lía return to their favorite elective class. In this new adventure, Queen Runa is assembling an army of replicas, and Lía and Ulysses must return to Eternia as quickly as possible to help their friends, ...

In this fifth book, Ulysses and Lía return to their favorite elective class. In this new adventure, Queen Runa is assembling an army of replicas, and Lía and Ulysses must return to Eternia as quickly as possible to help their friends, the Eternians. Lía suggests that Professor Hache should come with them, but he flatly refuses. Why? What is stopping him from going with them? What secret is the professor hiding?