When I got back to the hotel I hurried through the lobby in case Marie was on duty, alive with questions about my evident shopping trip. Each time I shut the bedroom door behind me and flopped on the bed I felt a rush of relief. But this time as I lay on that bedspread, staring at the Monet print, the plan was beginning to take more detailed shape, like a small, dark cloud thickening on the horizon.

It started with a dog.

I remembered a story that Big Jacky once told me, about a fella who used to bet on greyhounds, and a wee scam he had going to fix the races. The owners of the greyhounds kept their prized beasts in the backyards, monitoring their diet carefully in the run-up to a race, coddling them like fragile plants in a frost.

But the night before a race this fella and his friend would go around chucking steaks over the yard wall to the dogs they wanted to lose, and the hungry animals fell upon the gift of meat with slavering joy. Come the big day, to the bemusement of their owners, these dogs – normally flashing miracles of muscle and rippling grey silk – would toddle out of the enclosure with all the urgency of a bloke offered his third helping of Christmas pudding after the Queen’s Speech.

And I remembered, too, that McGee had a dog: a sleek, densely powerful Alsatian called Major in which he took palpable pride. Major was tethered in his yard, apart from when McGee took him on parade round the streets, inspecting the sites from which he and his da collected ‘donations’.

The dog wasn’t mistreated – McGee was too meticulous about it for that – but it didn’t have much of a life: it was all hard, cold angles and short leashes, between the yard and the street and the outside kennel, and God knows there wasn’t much warmth emanating from McGee. The animal doubled up as a security guard. No one would dare attempt to get into McGee’s house through the backyard when the dog was there. Major was ferociously alert. Sometimes you could hear him barking at the milk van or the postman.

That’s the thing about a dog: when you have one, you start to rely on it. It’s human nature to trust a dog, even among those who show very little humanity to speak of. I read once that Hitler had his dog Blondi with him in the bunker, and he appeared to be utterly devoted to her right up until the moment when he ordered his cyanide pill to be tested on her, watching as the capsule was forcibly crushed between her long, elegant jaws to make sure that it was fatal.