Set in Bilbao, the show revolves around Sergio Ciscar, who has recently been released from detention. He has been temporarily mute during his childhood following to a traumatism and has recovered his faculty of speech only when his parents adopted a little sister. He has spent six years in detention for parricide and is now under the secret watch of a young psychiatrist, Ana Dussuel, and her team. She loves him secretly and she also receives help from Marta, a girl obsessed with Sergio.
Sergio desperately tries to find his younger sister, who was the only one in his family who treated him nicely.
During the course of the series, it’s discovered that Sergio is a genius quick to anger and that his mother, a psychiatrist, was experimenting on him without his father's consent/knowledge.
Towards the end we find out that Sergio is unstable and was on drugs and lashed out and pushed his parents over the balcony of their apartment to their death.
The police are also involved in the watch, but are corrupt and trying to derail the watch.[1]