On the island of Ischia, Elena runs into the Sarratore family, reigniting her childhood crush on Nino, who is at odds with his father, the charming Donato. Back in Naples, Lila's resistance to Marcello's pressing courtship reaches a breaking point. On the day of Elena's 15th birthday, an unexpected encounter leaves her shaken.

At Rino and Pinuccia’s wedding, Elena accepts Lila’s invitation to go on holiday, provided the destination is Ischia, where she knows she’ll find Nino. On the island, Elena, Lila and Pinuccia begin to spend more and more time with Nino and his friend Bruno and Lila starts to take a strong interest in Elena’s summer reads. As Lila and Pinuccia exhibit signs of nervousness when their respective husbands come to visit for the weekend, Elena is thrown when Lila comes to her bedroom to make a confession.

As Pinuccia returns to Naples, a new secret excites Lila and numbs Elena, who nonetheless becomes embroiled in its coverup. Subdued by Lila's charisma and indifferent to Bruno's flattery, Elena finds herself the keeper of a far darker clandestine series of events involving Donato Sarratore. After the girls encounter Michele and Gigliola, who have come to Ischia on a day trip, Lila seizes the opportunity to throw the whole truth in Stefano's face.