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.

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.