"Tras el desenlace de la cuarta prueba, Laia y El�ias se ven obligados a huir de la ciudad de Serra perseguidos por un ej�ercito de m�ascaras. Ahora, su �unica esperanza es Darin, el hermano de Laia, cuyos conocimientos sobre el acero s�errico son la clave para el futuro de los acad�emicos. Pero Darin se encuentra encerrado en la prisi�on de Kauf, la m�as inexpugnable y peligrosa de todo el imperio. A pesar del riesgo que supone, Laia est�a decidida a liberar a su hermano y Elias resuelto a seguir a su lado, aunque ello suponga renunciar a su propia libertad."--Casadellibro.

After the events of the Fourth Trial, Martial soldiers hunt the two fugitives as they flee the city of Serra and undertake a perilous journey through the heart of the Empire.

Laia is determined to break into Kauf - the Empire's most secure and dangerous prison - to save her brother, who is the key to the Scholars' survival. And Elias is determined to help Laia succeed, even if it means giving up his last chance at freedom. But dark forces, human and otherworldly, work against Laia and Elias. The pair must fight every step of the way to outsmart their enemies: the bloodthirsty Emperor Marcus, the merciless Commandant, the sadistic Warden of Kauf, and, most heartbreaking of all, Helene - Elias's former friend and the Empire's newest Blood Shrike. Bound to Marcus's will, Helene faces a torturous mission of her own - one that might destroy her: find the traitor Elias Veturius and the Scholar slave who helped him escape... and kill them both.

In Spanish.