Ben Yusuf invades the Muslim Taifa of Zaragoza, igniting a broader campaign to conquer the Iberian Peninsula. In response, the embassy of warning travels to Castile as the ruler learns of Yusuf’s advance, and the young prince Al-Mu'tamin finds a path to escape to Castile to inform King Ferdinand.
In Castile, Rodrigo Díaz de Vivar enjoys a life of privilege as the son of the seasoned commander, Don Diego Laínez de Vivar. He is tightly knit with his best friend, the future king Sancho II, and he shares a secret romance with Jimena Díaz, the daughter of the formidable Conde Gormaz. Gormaz disapproves of the match and pushes Jimena toward a marriage with the haughty Conde Ordóñez. When the royal court learns that the Almoravids are crossing the Castilian border, Rodrigo joins Sancho, Ordóñez, and Gormaz on a scouting mission near Zaragoza.
At their camp, Gormaz is ambushed by Al-Mu'tamin and his warriors, but Rodrigo acts decisively to intervene. After the encounter, Al-Mu'tamin earns a place in their company, and Sancho allows him to accompany them back to Castile.
Sometime later, the powerful and calculating Urraca, the princess who holds the throne’s strings, orchestrates trouble: Sancho is marked for assassination to clear the path for Alfonso to be crowned. On a balcony set to Jimena’s request, Rodrigo asks for Jimena’s hand in marriage, but Gormaz, fearing he’ll be displaced, refuses and instead challenges Rodrigo to a duel. As the duel unfolds, Urraca’s traitorous ally strikes, stabbing Sancho in the back, while Rodrigo’s blade unexpectedly ends Gormaz’s life. Jimena, overcome with grief, withdraws from Rodrigo, who is forced to flee Castile.
Alfonso II? No, Alfonso VI is crowned, and Rodrigo’s steadfast refusal to kneel before the new king triggers further conflict. He swears that he had nothing to do with his brother’s death; Alfonso pretends to accept the pledge but banishes Rodrigo in anger and humiliation. Cast out, Rodrigo flees to Zaragoza, where his loyal friends Álvar Fáñez, Garcés, and Al-Mu'tamin welcome him back into the fold.
Under Al-Muqtadir’s Emirate in Zaragoza, Rodrigo and his companions devise a bold plan to reclaim the emir’s castle. Garcés helps by bringing in his adopted badger, and together they infiltrate the fortress, freeing Emir Al-Muqtadir and other enslaved Muslims. Rodrigo earns command of Al-Muqtadir’s forces and begins recovering lands and castles that Yusuf seized in the king’s name, gradually earning the Muslim title El Cid.
News from Castile summons Rodrigo back to face the king. He returns alone and confronts Alfonso, who pleads for aid against Yusuf, who intends to seize Valencia. Rodrigo questions the king’s motives and refuses to join a plan he sees as treacherous, which leads to imprisonment. Urraca later ventures into Rodrigo’s prison cell and attempts to sway him with seduction, but he resists. She then offers the same dagger used to kill Sancho and frees him, but only if he kills Alfonso. Rodrigo exits and visits Jimena, who has now fled to Valencia, though she remains wary of him for the moment.
Back at court, Don Diego Laínez denies any prior involvement in Rodrigo’s actions, and Alfonso has Urraca arrested as the machinations in Castile come to light. Jimena, torn by love and loyalty, follows Rodrigo toward Valencia, but Ordoñez pursues her and they are captured by the emir Al-Qadir, an ally of Yusuf.
Rodrigo and his men infiltrate Yusuf’s fortress, aiming to open the gates and allow a siege. Their plan falters when Yusuf’s forces tighten the defenses, and Rodrigo is compelled to surrender when Yusuf menaces Jimena. Yet the friends escape, and Garcés opens the castle gates for a renewed assault. The ensuing siege sees Rodrigo’s forces challenged by Yusuf’s amassed troops. In the climactic duel, Yusuf gains the upper hand but is finally disarmed and defeated as Ordoñez and Jimena escape. When Alfonso and his troops arrive, Yusuf makes one last attempt to kill Rodrigo, only to be thwarted by Jimena’s intervention, who retrieves Rodrigo’s sword and helps him finish the victory.
In the aftermath, Alfonso grants Rodrigo a pardon and blesses his union with Jimena, while Ordoñez makes amends and pledges to join them on their journey to Valencia, where Rodrigo is granted dominion over the lands he has fought to reclaim.
