In a story of theft and security lapses, “Fedora Man” is a gentler counterpoint — a teenager who believes art, style and a good mystery belong to ordinary life. One photo turned him into a symbol.

French salesman Dagobert Renouf had been dreaming of marrying his fiance Anna Plynina. The only thing between him and his dreams was the fact that he couldn’t afford the wedding. He did not want to ...