It's time to visit Aragon to nominate Prince Juan as heir to the kingdom, but this is the least of Isabel and Fernando's problems. Granada invades Zahara, Catalonia is divided and the royals must face their most dangerous pregnancy yet.

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.

Fernando makes his authority in Aragon clear. Isabel receives a foreign sailor with a bold proposal. El Zagal rallies all Muslims to make common front against the Christians.

Just as the Granada War nears its end, Prince Juan's sudden illness threatens to give Isabel and Fernando's kingdoms to the Portuguese. Columbus retouches his plan, and Torquemada investigates a murder.