It’s a high-class but increasingly common problem: being a former magazine editor in a digitized world that cares little about whose name used to be on top of a defunct masthead. (A masthead, for those unfamiliar with the term, lists in careful hierarchy the top staff of a publication and is most often printed on paper — which tells you pretty much all you need to know.)

At 48, Dan Peres is already an old hand at being a former magazine editor. Condé Nast shut down Details, the men’s glossy that he had been editor of for 15 years, in 2015. Overnight Mr. Peres went from two decades spent as a coveted presence at fashion shows and parties in the world’s capitals to a divorced dad adrift in the ’burbs.

He tried to pivot to digital publications, but quickly learned there is little job security in start-ups. He took on some consulting gigs. He was also jotting down stories from his past life, one not many people knew about.

“I started to have some conversations about next steps career-wise, and during that time I started writing,” Mr. Peres said last week, sitting in his home office in Irvington, N.Y., at a wooden drafting desk that he had lugged from Paris. “There were experiences I wanted to get down on paper. I wanted to keep my mind sharp.”