Isabel's decision to take the Crown while Fernando is in Aragon angers him, a division that Carrillo is eager to use. Meanwhile, Diego Pacheco seeks support from Portugal and the nobles to dethrone Isabel in favor of Juana.

Reconciled, Fernando and a pregnant Isabel face their biggest test yet as the Portuguese invade Castile. King Alfonso marries Juana to reinforce her claim, but is reluctant to consummate the marriage as his supporters insist him to.

The King's long absence throws Portugal in confusion, but Isabel and Fernando are no less divided over their next move. Rome pressures Castile to adopt the Inquisition. In Granada, the jealous Aixa plots against the Emir.

The war bogs down as the nobles of Spain prefer to pursue their own interests before the Crown's, but a stroke of luck might tip the balance in the fight between Christians and Muslims. In Portugal, the king seeks to reinforce his position.