Still, distractions follow him. Mr. Saviano is visiting Naples at a time, as he put it, of “tension.” He has placed himself squarely at the center of criticism against Italy’s new populist government, and raised the ire of Matteo Salvini, a right-wing, anti-migrant deputy prime minister.

In July, Mr. Saviano posted a photo of a dead woman and child floating in the Mediterranean Sea on Twitter, asking “how much pleasure” Mr. Salvini derives from walling off migrants. “The hatred you have sown will overthrow you,” he tweeted.

The spat has been a public sensation in Italy, combining the particular mix of respect and hatred that Mr. Saviano engenders. Some have cheered his blunt commentary, but recent elections suggest that many Italians agree with Mr. Salvini’s hard line on immigration. Mr. Salvini has threatened to sue Mr. Saviano and take away the state-sponsored escort. On the page and in life, drama chases Mr. Saviano.

“It’s my karma,” he said. “I go from trouble to trouble.”

Bearded, his balding head covered with a baseball cap, Mr. Saviano has a soft voice and a sense of humor. (He bowed his head in front of a box of Napoletano pizza. “A sacred moment,” he said before digging in.) He doesn’t seem much like a threat. But he is. Even asking if he has a significant other seems too much a risk.

This Is No ‘Baby Gang’

The title of “The Piranhas” in Italian — “La Paranza Dei Bambini,” or “The Fishing Trawler of Children” — is arguably more evocative, suggesting the tiny fish who are attracted to a bright light by nighttime nets meant for bigger fish. It is the first of two novels; the second, “Fierce Kiss,” is scheduled for translation into English in 2020.

Both tell the story of a gang led, in the novel, by a clever but coldhearted high school student, Nicolas Fiorillo. He is charismatic and quotes Machiavelli like a knife. He believes that the old gangsters who controlled drug running in central Naples have become weak and decides to take over the business. This is no “baby gang,” but a real enterprise of young criminals who did not come up through the Camorra, Naples’s dominant crime group. Instead, they are like hundreds of thousands of young unemployed Italians who see little hope in following their parents’ career paths.