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.

Fernando besieges Burgos while the Portuguese try to send a relief column to the rebels. Meanwhile, Isabel balances the conflicting interests of the Aristocracy, the Church and the Jews to finance the war.

Isabel debates showing mercy to the rebels when the new bread tax causes an uprising in Segovia. Chacón ponders retirement. Juana feels imprisoned during her husband's absence and seeks solace in her stepson, the Prince of Portugal.