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.

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.

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.