He recounts the investigation of two national police officers designated as infiltrators of the case of the disappearance of a seven-year-old girl, police officer Victor Reyes and Inspector Laura Cortés; and the investigation of his superior, Commissioner Casas. On the day of her first communion, Alicia Vega, a seven-year-old girl, disappears without a trace. After two weeks of intense search, the police have only one thing in clear: the culprit is one of the guests to the ceremony and a member of the girl's family. Agents Victor and Laura pretend to be a newly arrived marriage to the village of Cienfuegos, and infiltrate the environment of the Vega family and the rest of the suspects. While they remain in the shadow, Commissioner Casas is the official part of the investigation and the only person who knows the true identity of their undercover agents.