The civil war in Castile comes to its most decisive point as the armies of Enrique and Alfonso face each other in Olmedo. In Segovia, the Queen prays for her husband and Isabel for her younger brother.

Isabel and Fernando marry in Valladolid with the support of several nobles and are acclaimed by the people. However they are cousins and the marriage needs a Papal bull to be valid.

Hearing good news from Rome, Enrique makes his new move by blockading Valladolid. With no food for the winter, the people's support for Isabel and Fernando vanishes. Fernando also grows sick of Carrillo's meddling.

Isabel and Fernando find refuge in Medina de Rioseco but their situation is dire. Pacheco's army is on the move, ready to punish their supporters. Fernando suspects of Carrillo, while news of her husband's infidelity drive Isabel mad.

Cabrera convinces the King to receive Isabel and Fernando in Segovia. Away from the Court, Pacheco offers Queen Juana his support while he plots to kidnap Isabel and her daughter.