Clarke gave a groan, but she couldn’t help grinning too. It felt like the first time she’d cracked a genuine smile all day.

‘Mr Cafferty’s up on the roof terrace,’ Andrew told Rebus as he opened the door to him. Rebus nodded and made show of spreading his legs and arms, but Andrew shook his head. ‘You’re no longer perceived as a threat.’

‘You might want to reconsider that,’ Rebus said. Then, ‘What were you doing down Constitution Street?’

‘What do you mean?’

He affected a shrug. ‘Thought I saw you there. Just wasn’t sure if it was me or Fraser Mackenzie you were interested in.’

‘I’ve no idea what you’re talking about.’

‘Must be a case of mistaken identity.’ Rebus met the taller man’s eyes. ‘But if it was you and you were trying not to be seen, you need to sharpen up. Same goes for that stunt you and your boss pulled with DI Clarke and her team. Haven’t seen me in weeks and reckon I must be going senile? I’m guessing the security cameras in the concierge office will tell a different story. If you’re going to lie to a murder inquiry, it has to be watertight. Wee tip for you there.’ He patted Andrew’s shoulder. ‘Now let’s go see the cripple before he turns into Jack Nicholson at the end of The Shining.’

The roof terrace stretched the length and width of the building, hemmed in by waist-high glass panels and accessed by a glass-walled stairwell that had been fitted with a stairlift.

‘Mr Cafferty says you can use it if you like,’ Andrew commented as they passed the machine.

Rebus took each subsequent step with more determination. He patted his jacket pocket, making sure he had his inhaler, before stepping out onto the roof into something not far short of a gale. A few contemporary sculptures and a lot of potted plants had been added to the space. The plants looked lifeless, hunkered down until spring. Rebus was tempted to join them, but instead he zipped his jacket up to the chin and hid his hands inside the sleeves.

Cafferty was in a portable wheelchair rather than his electric. He sat at the very centre of the terrace. Rebus did a slow turn, the city and its rooftops spread out around him.

‘Impressive, no?’ Cafferty said. His mittened hands were pressed down against the tartan travel rug covering his lap and legs, stopping it from flying away. He wore a plain maroon beanie on his head and a scarf of the same colour around his neck. The only lighting was at floor level, so that his face remained largely in shadow.

‘How many days a year can you come up here, though?’ Rebus queried. ‘Without the fear of hypothermia, I mean?’