One day in early November, 2014, I arrived at a little book shop facing Notre-Dame in Paris and sheepishly explained to a staff member that a friend of a friend had said that I could perhaps sleep here, in the book shop, while I researched my new novel, Let Us Be True. I half expected them to start laughing at me, but instead, they led me to the back, up the stairs, through a little library with beaten up leather armchairs, unlocked a door to a stairway landing, unlocked another door, and led...