Anderson shrugged. ‘Other than the fact the back of his head is caved in, your guess is as good as mine. Bolton and Stenner are nowhere to be seen. There’s a fire escape leading down the side,’ he said, pointing at a door in the far wall, ‘but by the time we checked for signs of life with these two, and cleared each floor, there was no sign of anyone else. We’re fairly sure Bolton came in here with Carter, but he didn’t come out the front, I know that much, so that’s our best guess for now.’

Porter looked down at Gibson again. His thoughts immediately went to the picture on Gibson’s desk at work, a family shot with his arms around his wife, and their sons like bookends to their left and right. They would have to be told.

Pity the poor bugger who pulls that duty.

‘What about the building?’ asked Styles. ‘Why here?’

‘No idea,’ said Whittaker, speaking at long last. His face was pale, and a sheen of sweat on his brow hinted that he was still struggling with what they had stumbled into. ‘We’ve not come across it before, but we can check it out at Companies House when we get back.’

‘Any idea what they used on Gibson?’ asked Porter.

‘Over there.’

Anderson pointed a few feet past where Gibson’s body lay, to a piece of wood around four feet long. Even from where he stood, Porter could see the wispy strands that clung to it where a jagged edge had torn a clump from Gibson’s scalp when it had connected. The hairs of the light grey clump were bound to the wood by a congealing streak of blood. The contrast of the colours and the way the tuft stuck out reminded Porter of a fly-fishing lure.

Porter stared for a few more seconds, soaking in the scene. His eyes lingered once more on Gibson, then the door frame, feeling his anger rising. He clenched and unclenched his fists.

‘Come on, then,’ he said, addressing the three of them. ‘Every extra minute that bastard is left to strut around town is an insult to Mike and Evie.’ His use of the officers’ first names somehow made it even more personal to them than it already was. ‘A man his size can’t be too hard to find, even in this city. Let’s bring him in.’

They left one of the uniformed officers from downstairs to guard the scene on the first floor. Anderson and Whittaker had been working the Locke case for six months solid and had a good handle on Bolton’s usual haunts. He gave Porter and Styles addresses for Bolton’s office, as well as for the few businesses they knew he owned. He split a further eleven possibilities between the other officers who were outside on the street, opting to keep Bolton’s home address for himself and his partner.