The disappearance of her old friend Lila causes author Elena to look back on the early days of their friendship during the 1950s in Naples, when they were two drastically different girls at the top of their class.
Elena grows tired of Gino, while Lila rejects two potential suitors at a cost; a rare outing into the city turns violent; Elena worries about not being there for Lila after accepting an invitation to spend the summer away from the neighborhood.
On the island of Ischia, Elena runs into the Sarratore family, reigniting her childhood crush on Nino; Lila's resistance to Marcello's pressing courtship reaches a breaking point; an unexpected encounter leaves Elena shaken on her 15th birthday.
Elena returns to Naples and finds out that Lila is romantically involved with Stefano, despite Marcello's advances. While Lila embraces that luxurious lifestyle Elena decides to reciprocate romantic advances.
The shoe sales are slow, so Stefano makes a deal with the Solares despite Lila's objections. Elena is thrown out of class for expressing her mind, she writes an article about that. Lila's wedding day arrives.