“Professore Quattrocchi missed our dinner date, and he hasn’t been answering my calls. I’m worried. Has he contacted the university?”

She shook her head no, but this time, I thought I detected some concern.

“I’m worried,” I said again. “Does he usually stay away without calling, without contacting you?”

“The professore has been through much—with his loss. I do not wish to disturb him.”

“But not to call, to drop his classes, just like that? I want to see him to make sure he’s okay.”

Signora Moretti hesitated, sighed, then nodded. “His home is near Santa Croce.” She wrote the address on a piece of paper and handed it to me. “You will please to let me know the professore is fine.”

I put Quattrocchi’s address into Google Maps and followed the route, holding my phone out in front of me like a divining rod. It led me past the Bargello Museum, which I had been meaning to visit to see Donatello’s young David, a sculpture that many art historians believed had kicked off the Renaissance, one more artwork I had taught and never seen. The crenellated building dominated a small square and blanketed the surrounding streets in shadow. If I was reading my GPS correctly, I was heading southeast, away from the historic part of the city into a less populated neighborhood, along one angled or curving street to another, buildings shifting from warm grays to tans to sienna and even rose. I could feel the presence of generations, the weight of it in the stone walls and peeling paint, could smell it in the air, almost taste it, not just the city’s age but its history, and I was enjoying it.

My enjoyment stopped about the same time my GPS quit and I hit a dead-end street and had that feeling again, of being followed. I retraced my steps, wasn’t sure if I was being paranoid, but my radar had saved my ass more than once, and I’d learned to trust it. I found my way to a wider, busier street—the whole time looking over my shoulder—and my Google Maps came back to life.

I kept my eyes glued to the little blue ball on my phone’s map so I missed the fact that the neighborhood had become rougher and grittier, ugly old buildings mixed with ugly new ones, more trash and graffiti than I had seen anywhere else in the city. I was glad when my GPS directed me onto a kind of neighborhood thoroughfare, one side lined with bicycles, the other with motorbikes, dozens of them all perfectly angled. Another block and I found Via dei Pepi, Quattrocchi’s street, the sign high up on a drab tan wall showing serious symptoms of water damage.

Via dei Pepi looked too narrow for cars, which gave it a back-alley quality, though it still had charm, some of the houses with newly painted shutters on upper windows and lovely metal work covering the ones on street level, though I realized they also served as bars. Several houses had cracked stone surfaces and more water erosion, but others showed obvious signs of gentrification, freshly painted facades and shiny new doors, and number fifteen—Quattrocchi’s home—was one of these. Three stories painted ochre bordering on yellow, shutters dark green, not a bit of peeling paint or water damage. The door looked new too, dark wood, and curved to fit into a stone arch, above it a half-moon transom of metal florets. In the center of the door, a dangling metal knocker. I lifted it and let it fall back against the wood, the noise sharp and hollow.