“My Brilliant Friend” is set to close the book on Elena and Lila’s journey. The Italian- and Neapolitan-language television series has been renewed for a fourth and final season by co-producers HBO and Rai.

Based on the acclaimed “Neapolitan Novels” four-book series by Italian writer Elena Ferrante, “My Brilliant Friend” follows the coming-of-age of two best friends, Elena Greco and Lila Cerullo, who grow up in a poor Naples neighborhood in the 1950s. As the smart-but-shy Elena continues her education and eventually ascends into the wealthy elite, the outspoken Lila is denied schooling by her family and struggles through an abusive marriage. The show, which is named after the first novel in Ferrante’s series, has adapted each book into an eight-episode season, with the fourth season set to adapt the final installment, “The Story of the Lost Child.”

The first three seasons of “My Brilliant Friend” have starred...