It’s the mid-11th Century. Ruy es a young man who has just been named squire to Prince Sancho, King Fernando of León’s eldest son. One night he discovers that someone he loves is involved in a conspiracy to overthrow the King. From then on, Ruy is caught between his loyalty to duty and to his heart.

Flaín is wants the man who upset the conspiracy. Rodrigo knows it was his grandson, which is why he intends to send him off to Vivar. On the other hand, Ruy resists leaving the King at the expense of Flaín, as he sees the only solution being to end the Count of León’s life. When it looks like everything is about to kick off, the Navarre troops turn up at the border and declare war against León.

Fernando sends his son, Sancho, with a small army to Zaragoza to confront his brother, Ramiro, the King of Aragon. Before leaving with Sancho, Ruy reveals to the King that Flaín tried to kill him. Fernando starts to investigate who betrayed him. Meanwhile, Ruy leaves León ignorant to the fact Flaín sent a hitman within the troop to kill him.

The Castile tropos with Sancho and Ruy fight an outnumbered battle against the Aragonese. When all seems lost, the outcome seems totally unexpected. In León, Fernando discovered who was conspiring against him.

After Fernando’s subsequent illness, Sancho and his troops return to León. Ruy tells his grandfather that Flaín sent someone to kill him. Rodrigo knows his grandson’s life is in danger. Flaín, on the other hand, doesn’t give up on his mission to conspire against the dying King and decides to attempt seizing power before his death. He is unaware that Urraca still has a card to play.

After the assassination of Flaín, the Count of Leon, many point at Ruy as the culprit. Meanwhile, the one from Vivar is forced to go back to Zaragoza, where he was sentenced to death for having lain with Amina, the Emir’s daughter. In Leon, Urraca finds out that Jimena and Ruy are in love, and schemes a plan to gain benefit from this information.

Alfonso, following Urraca’s advice, has one last tempting card up his sleeve to get Ruy to stay in Leon by his side: breaking off Jimena’s betrothal to Orduño and blessing her marriage to Ruy. Ruy will get everything he wants, but in exchange he will have to betray Sancho. Meanwhile, the Arabs, who are looking to destabilize the Christian kingdoms, tell Sancha that the King was poisoned.

After Sancha’s death, the war between the three brothers is imminent. Sancho sets out to attack Galicia, but in order to do that he must pass through Leon. Alfonso can’t decide whether to leverage that moment and attack him or to let him through. Meanwhile, Ruy struggles with the passion between him and Amina, and the pain that Jimena’s betrothal to Orduño is causing him.

After Ruy’s decisive intervention in the battle, Sancho of Castile takes Galicia from his brother García. But this does not bring peace to the Iberian Peninsula. On the contrary: the final battle between Leon and Castile is approaching. Meanwhile, Ruy is forced to betray Amina.

Sancho has decided to execute his brother Alfonso and the rest of Leonese nobles who support him, including Orduño. As soon as Alfonso is dead, Sancho will be crowned King of Leon, and as a reward for his services, he offers Ruy the title of Count when Orduño is executed. He can finally get everything he has dreamed of: nobility, lands… and Jimena. But there is something Ruy isn’t counting on.