Series premiere. Five years after a murderous school tragedy, a brutal crime brings together Benitez, the superintendent, Renzo Marquez, an ex-cop, and Laura Santini, a psychiatrist. They soon discover a tombstone which reveals the message 'never should have.'

Renzo and Martin decide to work together after Benitez's death. Their investigation leads them directly to the father of one of the kids who were murdered at the school. Meanwhile, Laura is forced to meet with Renzo; and an old debt inspires the next epitaph, which reads: 'the one who denied what's fair.'

Trying to find the identity of the killer, Renzo and Martin trace the steps of one of the suspects. Meanwhile, the fate of the one who was 'deceiving the game' will be written on a new epitaph. In the end, Renzo will be very close to his prey.

Renzo discovers a very important piece of information in the warehouse. Manuel once again goes to Laura's office. Meanwhile, there's a new victim whose epitaph reads 'the one who made darkness an obsession.' During a complex police investigation, Renzo receives help from an unexpected source. In the end, Laura and Renzo witness a sadistic and deadly event.

As the relationship with her ex-husband becomes increasingly tense, Laura discovers new information about the killer. A new epitaph is found near another body, and it reads 'the one who ignored the misfortune will answer at all times.' Laura believes she knows the identity of the next victim. Renzo, the killer and the victim will be very close at the airport.

Frustrated by the events at the airport, the killer decides to reveal his name to Laura. In the meantime, an unexpected and gravely injured visitor arrives at Renzo's house and Martin receives information that could lead him to the killer. By the end, a new epitaph reveals that somebody 'who lived at the wrong time' could die the same day.