Sergeant Sara Campos tries to recover and finds a clue that brings her closer to finding Lucía. Ana begins to lose her fear and trust Quim. The facts are increasingly evident that the kidnapper lives among the residents of Monteperdido.

The Civil Guard arrest the first suspect in the case and the town of Monteperdido is not too happy about it. The agents are getting closer to the truth, but the locals feel uncomfortable with the investigation and feel treated as if they were all suspects. When Corporal Víctor Gamero learns about this, he confronts Sergeant Sara Campos. Meanwhile, Ana tries to go back to a "normal life," which is not easy at all. Her return has brought to light old secrets that will put the lives of some of the residents of Monteperdido at risk.

Lieutenant Baín and Sergeant Campos begin to piece together the years when Ana and Lucía were kidnapped. They learn more and more about the kidnapper and slowly get a better understanding of the hell that the girls went through. Lucía's parents, however, especially Joaquín, are not willing to just sit and wait. They don’t hesitate to use Ana to try to hasten the events and find Lucía as soon as possible. But a development leads to a dramatic turn in the course of the investigation and in the life of Sara Campos.

Lieutenant Santiago Baín and Sergeant Sara Campos know that they are in Ana's hands. The girl who has returned after being kidnapped for five years is all they have to find out what happened.

The whole truth comes to light and the lives of the residents of Monteperdido will never be the same. Sara puts her mental health at risk and refuses to give in. She will not leave Monteperdido until she accomplishes what she came here to do: find Lucía.

Ana and Lucía go missing in Monteperdido after they leave school. Five years later, one of the girls reappears; she has been in a car crash. She is unconscious and the driver is dead. The news will turn the lives of the affected families upside down. UCO agents Lieutenant Santiago Baín and Sergeant Sara Campos arrive in town to take charge of the case. The investigation turns out to be a race against the clock. With the help of Corporal Víctor Gamero, they will have to solve two fundamental questions: who is the deceased man found in the car and where is the other girl who went missing five years ago?