He didn’t like that. ‘Be careful you don’t break your neck going down these stairs,’ he said. ‘It’s the kind of thing that can happen so easily. I’ll have to watch out on my way down. It would be too bad if I had an accident because I came up here to be of service to a neighbour. If you were to open your door and switch on your light, it would be a help.’

He’ll shove me in and rape me as soon as the door’s open, I thought. I pasted on a vacuous expression and offered a breezy, ‘Bye, then.’ It was obvious that I wasn’t budging, and he went away at last.

Five minutes later I followed him down, feeling my way along the wall. Rinaldi’s door was shut, but his music occupied the stairs – it often did, these days. His taste ran to the classical and arduous. It would be further proof of weirdness in the profile: The killer listened only to [insert name of composer]. I felt sure that his story about the mix-up with my letter was a lie. Rinaldi had helped himself to my mail in order to deliver it in person, hoping to be invited in.

At the mini-mart I bought a padlock for my letterbox as well as a bulb. Rinaldi’s music was still bullying its way out of his apartment when I returned. It gave the impression that he was safely inside, but how was I to tell? He could be waiting for me on the last, dark flight of stairs. Everyone who’s seen a horror film knows how it goes: an encounter that seems threatening proves harmless, and the victim lowers their guard. Then the killer strikes. I went up the stairs sideways, spine against the wall. My shoulder bumped the timer on my landing. The light sprang on.

Had the bulb fallen victim to Monsieur Laval’s wiring? It could have flickered out, and later flickered back into life. Another possibility was that Rinaldi had replaced it with a dud earlier in the evening to frighten me, and switched it back again while I was out.

I saw him a few days later, in the street leading to the cathedral. We were heading in different directions on opposite sides of the street, but he crossed over to put himself in my way. He informed me that he’d replaced the burnt-out bulb on my landing. ‘That very evening. Who knows how long our landlord would have taken?’ His smile was greasy with self-love. ‘I knocked on your door to tell you but you’d gone out again.’

Rinaldi didn’t have a southern accent. He spoke the bell-like French of newsreaders – it expected obedience. I was obliged to thank him for the favour of changing my bulb, just as I’d been obliged to thank him for bringing me my letter. ‘Please don’t go to any trouble if it happens again,’ I added. ‘I can change it myself next time.’