The disappearance of her old friend, Lila Cerullo, causes 60-year-old author Elena Greco to reflect on the early days of their friendship in 1950s Naples, when Elena and Lila are two very different girls at the top of their class.

As fourth grade draws to an end, Elena and Lila fight with their families for the chance to continue their education. Later, a trip out of town becomes a day Elena will never forget, and a death changes things in the neighbourhood forever.

Now a teenager, Elena grapples with the onset of puberty, her studies, and her friendship with Lila, who now works in her family's store. After a library awards ceremony reveals what Lila has been keeping secret, Elena learns what her friend's grand plans might be.

Entering high school, Elena vows to stay ahead of Lila, academically and romantically. Lila eschews a parade of suitors, choosing instead to focus on her ambitions in the store. Stefano Carracci promises a better future for the neighbourhood but things take a dark turn.

Elena grows tired of Gino while Lila rejects two potential suitors at a cost, and 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 neighbourhood and her family.

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

Elena returns to Naples to find Lila has made a romantic connection with Stefano, despite the looming presence of Marcello. As Lila embraces a more glamorous life at Stefano's side, Elena warns her about what people are saying around the neighbourhood.

With sales lagging, Stefano cuts a business deal with the Solaras against Lila's wishes. After Elena gets kicked out of a class for voicing her opinion, Nino asks her to write a magazine article about her experience. Later, Elena and Lila get unwelcome surprises.