Ana and Lucía disappear in Monteperdido as they leave school. Five years later, one of the girls reappears; she's been in a car accident. She's unconscious, and the driver is dead. This news will turn the lives of the affected families upside down. Lieutenant Santiago Baín and Sergeant Sara Campos, officers from the UCO (National Police Unit), arrive in town to take charge of the case. The investigation turns out to be a race against time: assisted by Corporal Víctor Gamero, they will have to answer two fundamental questions: who is the deceased man they found in the car? Where is the other girl who disappeared five years ago?