Island of Carloforte. The community is shocked by a tragic event: the explosion of the ancient Tonnara during a party among the high school students, in which four of them lose their lives. Dr. Pietro Sereni is the first to render aid, being injured. The event brings Elena, Pietro's daughter, back to the island after an absence of fifteen years, who will find herself facing her painful past.
Elena and Pietro manage to track down Caterina and bring her back to Carloforte. The girl wants to keep her pregnancy hidden but reveals to the investigators that drugs were circulating at the party. Elena is convinced that Samuele, Alessandro's brother, is involved in the Tonnara affair, and this is the cause of new clashes between them.
While Elena continues to investigate to exonerate Caterina, who has taken refuge in the Sereni house, Pietro realizes that Diana is pretending to have lost her memory. Giovanni arrives unexpectedly in Carloforte, noticing the attraction between Alessandro and Elena. Meanwhile, on the evening of the feast of the patron saint, Diana disappears.
Diana's misfortune shocks the community, already tried by the tragedy at the tuna fishery. Thanks to Pietro, who reveals to Elena and Alessandro that Diana was a prostitute in Cagliari, it turns out that Caterina had also been to the guesthouse where Diana went with her clients. At this point Elena leads the little girl to the police station, determined to force her to confess the truth.
After the arrest of Enrico, guilty of Diana's death, the investigation into the fire at the tuna fishery continues: Elena is increasingly convinced that Samuele's hand is behind it. Pietro takes care of Riccardo, who needs to undergo heart surgery. Meanwhile, Caterina begins to have doubts about her birth, while Alessandro investigates to discover the identity of Elena's attacker, the fateful night fifteen years earlier.
While Samuel is found murdered in his home, Elena and Pietro find Alessandro on his boat, in shock and covered in blood who accuses himself of the murder of his brother. While Elena tries by all means to exonerate her beloved, Pietro senses that Grazia is still hiding something about Caterina's birth...
Island of Carloforte, Sardinia. After a bad accident, Caterina still can't remember the details while the relationship between Alessandro and Elena, who suspects an affair between the man and the deceased Giulia Canale, is increasingly tense. Meanwhile, Pietro tries to keep up with Diego who, while continuing to work for the drug dealer Walter Sasso, meets the son of a drug addict, little Tobia in need of help.
Pietro takes care of little Tobias, who is in a medically induced coma after a heroin overdose. While Diego is the only one who understands Caterina, the rift between Elena and Alessandro seems irreconcilable. When the culprit of Giulia's murder seems to have been brought to justice, Vanessa Silas disappears after a beach party... Vanessa Silas' search continues unabated, Elena involves Alessandro in the investigation, but she can no longer trust him. While Caterina quarrels with Fabrizio, Diego discovers the disturbing truth related to her birth and clashes with Pietro. Meanwhile, Ignazio Silas receives a ransom letter...
Pietro is involved by Fabrizio in his family crisis, the boy's father seems to have a lot to hide and is perhaps connected to Vanessa's disappearance. Diego searches for the truth about his family by distancing himself from Caterina while Elena is in the throes of strange physical ailments... Vanessa's tragic death shocks the entire community of Carloforte. Elena and Alessandro, under pressure, stop a Nigerian immigrant, Samir, in whose shelter the scarf of the deceased is found. Pietro is very worried about Diego while Caterina meets the famous ophthalmologist who, perhaps, could operate on her and restore her sight...
The investigation into Vanessa's murder continues. Matteo, to whom the girl transmitted HIV, is stopped and interrogated. As Diego reconnects with Caterina, Pietro discovers that Elena is expecting a baby and tries to convince her to talk to Alessandro about it. Meanwhile, Patrizia, the bartender, seems to be hiding a secret... While Elena is forced to stay in the hospital and Alessandro convinces Caterina to get back on the windsurf board, Pietro discovers that the supplies of HIV drugs have disappeared and that Patrizia lied about the time she contracted the virus. Diego is unable to confess his love to Caterina, risking getting into trouble...
While Caterina is unable to confess to Diego that she has left Fabrizio, Elena and Pietro find Alessandro unconscious at Villa Lai. Ferras, unconscious, is transported to the hospital. By now it is clear that between the death of Giulia Canale and that of Vanessa Silas there is a connection... Peter has to undergo a delicate operation on Tobias and in the meantime he gets closer and closer to Isabella. While Alessandro recovers, all the clues lead us to believe that the culprit of the attack is Diego, who has been taken to prison. Caterina, convinced of the boy's innocence, pushes Elena to continue the investigation that reveals a disturbing truth about the death of Diego's parents.
Peter is sorry because Isabella is strangely elusive. But maybe she and her ex-husband Saverio Sulci are hiding something that could concern Diego. Caterina would like to train for the windsurfing crossing, but Elena fears it is too dangerous and this reignites the conflict in the family. Meanwhile, Elena and Alessandro continue their investigation into the death of Mr. and Mrs. Lai. Little Tobias can finally hug his father Sergio again. Elena and Alessandro are on the trail of Rudy Sulci: he is the main suspect for the death of Mr. and Mrs. Lai and perhaps also for the murder of Giulia Canale. When Catherine leaves the house and then disappears, everyone's concern grows. Peter thinks of asking Isabella for help as well. Although recent events have made their relationship with each other more difficult, the woman's mutual affection and gratitude for Peter are sincere. Meanwhile, Pietro has to face another very delicate situation: revealing the truth about his parents to Diego...
Elena and Caterina will be returning from Houston. The teenager has just had eye surgery and is eagerly waiting to see if she has recovered her sight. He will also have to deal with Diego's ambiguous attitude, which seems to be hiding a secret. Pietro manages to save a newborn girl from a fire for which the investigation immediately begins to find out who her mother is. Elena will find it difficult to work together with the new Deputy Commissioner.
Catherine has recovered her sight, so she is trying to regain everything she lost in her period of blindness. Diego confides his secret to Pietro: he had an affair with Chiara and the child could be his daughter. Elena and Valerio, meanwhile, manage to trace the identity of a new suspect who could lead to a breakthrough in the investigation. Chiara, in fact, may have had an affair with her literature professor.
Investigations continue to uncover the truth about Chiara's death. It is difficult to trace the murderer, since the young woman's acquaintances do not cooperate. A trail seems to lead to Stefano Orrù. Meanwhile, passion breaks out between Valerio and Elena. Peter, on the other hand, will discover a shocking secret.
The discovery at the resort of the dying maid Lara seems to mark a turning point in the investigation into Chiara's death. Franco Puerto Rico, Lara's alleged father, is the prime suspect in both murders. Meanwhile, Pietro tries to stay close to Ilaria in chemotherapy while Caterina informs Elena of her decision to leave Carloforte with Leonardo.
The search for Irene Manca, who has kidnapped little Anna and seems to have disappeared into thin air, continues feverishly. Diego tries to find her by any means thanks to Pietro's decisive help. Elena and Valerio seem close again. While Catherine ponders her departure, Leonardo finds himself in serious danger. Meanwhile, the investigation into Chiara's death leads to the trail of a car seen near her father's construction site, but all is not as it seems. Meanwhile, Valerio and Elena have to deal with some complications, now that the relationship is becoming more and more serious. In the meantime, Caterina has decided not to leave with Leonardo, but the affection she still feels for the boy could put her in danger.
What was the intruder looking for when he entered the police exhibit warehouse? Elena and Diego investigate an ordinary sweatshirt found out of place. Valerio, meanwhile, tries to mislead his colleagues, but is forced to face a new unforeseen event. Meanwhile, Catherine hopes to reconnect with Diego, but her hopes seem to be held back by an unexpected revelation, and Pietro will have to help his niece deal with her. The circle around Chiara's killer is tightening: Monica confesses to the murder, but perhaps she is only covering up for someone. Maybe his daughter Stella? Meanwhile, Pietro will have to stay close to Diego, who is increasingly convinced that he wants to build a new family with Margherita. Elena and Valerio are in a difficult moment, so much so that the policeman is thinking of asking for a transfer.