Elena Ferrante’s novels are beloved. Her identity remains a mystery

Seemingly overnight, Elena Ferrante — or rather, the novelist writing as Elena Ferrante — found worldwide acclaim.

Her novels were everywhere: You couldn't swing a tote bag without spotting one of her pastel-hued paperbacks on the subway, at the beach, in the airport.

The four novels that make up the Neapolitan quartet rocketed her to fame. Beginning with "My Brilliant Friend" in 2011, the books, which include "The Story of a New Name" (2013), "Those Who Leave and Those Who Stay" (2014) and "The Story of the Lost Child" (2015), chart the lifelong, charged friendship between two women in postwar Naples, Italy.

Readers appreciated the nuanced relationship between the main characters, Lenù and Lila, a delicate mixture of love, jealousy and abiding loyalty. Critics zeroed in on Ferrante's intimate attention to women's lives, both in the Neapolitan novels and in her...