Early 16th century: following the death of Isabel la Católica, her widow Fernando de Aragón enters in an open war with his tyrannical son-in-law, Felipe el Hermoso, lord of Flandes, who wants to be the new king of the kingdom of Castilla above all. In the middle of the conflict his wife Juana, Fernando's daughter, turns in the center of attention caused by her unstable mind state. Trying to preserve the kingdom for their descendants, Fernando asks help Cardinal Cisneros in order to make a deal with Felipe, but this one has his own agenda looking to expel Fernando out of the Castilla to claim the throne for him, avoiding any contact between father and daughter that it could be an obstacle for his ambitions. But will can Juana to mediate between the two men of her life to prevent a war between the kingdoms that it annihilates the legacy and will of her beloved and deceased mother, or her growing insanity will be the perfect excuse to start the war?