“We’ve had a bit of a crisis,” Hughes de Courson told me on a raw Parisian morning last February. I’d found him slumped at a table overlooking the cobblestones of the Place Émile-Goudeau, trying to mollify his much younger girlfriend, Naomie Assana. Courson explained that they had spent the previous night drinking a fair amount of wine in Versailles, and this morning their hostess had asked them to leave, claiming they’d kept her up all night. Exhausted, they had returned to the city and checked into this modest hotel in Montmartre.

Courson, a sixty-nine-year-old with shoulder-length gray hair and…