The Life-Changing Journey of ‘My Brilliant Friend’

In the fourth season of “My Brilliant Friend,” premiering Monday on HBO, the childhood friends and fierce rivals Lila and Lenù navigate marriage and divorce, motherhood, loss and middle age.

This is the final chapter, catapulting the protagonists from the 1970s to the 21st century against the background of Italy’s upheavals, and is based on “The Story of the Lost Child,” the fourth book in Elena Ferrante’s wildly popular Neapolitan series.

Writing in The Times, James Poniewozik called the show “one of the most incisive portraits of a lifelong relationship ever made for TV.” But this final season also ends a production project that started in 2016 and which all of its lead actresses agreed was the most important of their careers.

Margherita Mazzucco, 21, played Elena “Lenù” Greco, and Gaia Girace, 20, played Raffaella “Lila” Cerullo, through three seasons — from the characters’ adolescence to their 30s. Neither had acted before they were cast in 2017, but they are both now stopped on the street at home and abroad.

For the seasoned actress Irene Maiorino, 39, who plays Lila in Season 4, the show offered a chance to become better known outside Italy. And the already internationally acclaimed Alba Rohrwacher, 45, who narrated the series before being cast as the grown Lenù. Rohrwacher described the role as an “incredible journey” that “can only happen once in a lifetime.”

The four women met together for the first time on a recent muggy afternoon in Rome, to discuss passing the baton from one pair of Lenùs and Lilas to the next and whether there were heightened expectations now that Ferrante’s “My Brilliant Friend” had been named the best book of the 21st century in a recent New York Times survey. (They all laughed: They’d heard.)