Fuck, fuck, fuck, fuck, fuck.

In the next bay, Detective Sergeant Jo Cameron lolled against her harness, fiddling with the Thrummer she’d borrowed from the armoury. She was whistling to herself, something cheery and upbeat that Will could almost recognize over the Dragonfly’s engines. She didn’t look worried about going back to Sherman House, but then she hadn’t been there eleven years ago. She’d been too young. She’d been lucky.

Will unclipped his Whomper from the recharging rack and checked the battery for about the twentieth time: still fully charged.

In through the nose, out through the mouth.

‘Right, listen up, campers.’ Lieutenant Brand’s voice was curt and businesslike. ‘They’ve already had two visits from the Network this week; chances are they’ll be getting restless. So keep it tight! I do not want this turning into another episode of “Everyone Gets Their Arse Shot Off”. Understood?’

The trooper in the bay opposite crossed himself as he and his colleagues barked, ‘Ma’am, yes, ma’am!’

‘Good. ETA: forty-five seconds. Buckle up, people, it’s going to be sudden.’

At the last moment the Dragonfly leapt, twisting almost vertically to climb the side of Sherman House. Jo shrieked and laughed; Will closed his eyes and tried not to throw up. As the gunship fishtailed to a halt on the building’s roof, he released his death grip on the supports and unsnapped his safety harness, watching as the bays around him erupted into life.

‘First team: GO!’

The rear ramp swung open, exposing the rooftop in all its tatty glory. When the connurb blocks were new this was all lush, vibrant gardens, arranged around the building’s central well. Twisting paths for romantic walks, picnic areas, and sports facilities. Now it was an unkempt jungle, punctuated by the blackened circles of forgotten bonfires. Drifts of rubbish slouched in every corner like dirty, lumpy snow, and here and there, the tumbledown ruins of community buildings were visible through tangled rhododendrons and brittle brown ivy, their walls crumbling and vandalized.

The first team sprinted out into the undergrowth, searching for an entrance to the lower floors.

Huddled in the safety of the drop bay Will looked out on the blocks that made up the other three corners of Monstrosity Square. Two hundred and forty thousand people were crammed into these four huge, ugly buildings. No jobs, no hope and no future.

No wonder they’d all gone crazy.

From here, sixty storeys above the roasting streets, Glasgow was laid out like a vast, concrete cancer. It stretched in every direction, further than the eye could see, grey and dirt brown, sweltering in the evening light. Home sweet home.

A voice sounded in his ear, making Will jump: ‘Entryway is secure.’

The second team burst out of the Dragonfly, taking up positions. And then Beaton and Stein lumbered after them, dragging the bulky scanning equipment through the scrub. The bashed and dented canister trundled along on tiny wheels that quickly became ensnared in the yellow grass. They swore and cursed all the way. Amazingly their grasp of the profane was nowhere near as comprehensive or inventive as DS Jo Cameron’s.

Will checked his Whomper’s battery one last time, then stepped into the sweltering afternoon. In through the nose and out through the mouth…Everything smelled of dust and dry earth.

He scanned the landing zone, finally spotting DS Cameron meandering along the edge of the roof. She had her Thrummer slung casually over her shoulder-like a long, deadly handbag-her hands in her pockets and a smile on her face.

Will shook his head and joined the advance team.

They’d found one of the minor access escalators: a small plexiglass bunker squatting on the building’s roof. The transparent panes were all scratched, covered with fading graffiti tags, the plexiglass swollen and blackened in one corner, where someone had tried to burn the place down. The moving steps were gone, exposing a ramped tunnel that disappeared into the depths of the building.

Will looked down into the hole. ‘This the only option we have, Sergeant?’

Nairn nodded. ‘Aye, sir. If we want to steer clear of the main access points it’s this or we go down the outside on wires.’

Will tried not to shudder-there was no way he was going out over the edge of Sherman House on the end of a body-wire ever again.

Nairn gave the orders, sending Privates Dickson and Wright scurrying down the ramp into the darkness. He gave it a count of ten, then waved at the SOC team. ‘Beaton, Stein: you’re next. And keep the noise down this time! I don’t want every psychotic wee lowlife in the place using your bloody scanning equipment as a homing beacon.’

‘What do you mean “our scanning equipment”?’ Stein slapped the battered canister. ‘Just cos we’ve been lumbered with this shite four times in a row don’t mean we’re makin’ a career out of it!’

‘Shut your cakehole! You will hump that bloody scanning stuff about and you will like it. Or I will connect your rectum to your bloody ears with my boot!’ There was no smart reply from Private Stein, he just picked up his end of the SOC canister and clambered into the tunnel. Nairn nodded. ‘Better. Rhodes, Floyd: you’re on rearguard.’

Will picked his way carefully down the slippery ramp. Six feet in, the track twisted back on itself, doglegging around a support pillar, and as he turned the corner Will’s innards clenched. The toilets downstairs had been bad enough. But this was…This was…Jesus.

The breathing exercises weren’t working any more.

Stupid. It was just a building. Nothing to worry about.

So how come his legs wouldn’t move?

Inside, Sherman House hadn’t changed much in the last eleven years: dingy corridors, lined with silent, shuttered apartments. All the horrors locked away and secret. At least this time the carpets wouldn’t be sticky with blood.

Grubby plastic spheres lined the passageway, giving off a pale, insipid glow that did more to exaggerate the shadows than illuminate things. More graffiti lurked in the gloom, covering the beige walls like cheap tattoos. People trying to leave their mark on a world that had already forgotten about them.

Someone tapped him on the shoulder and Will flinched. ‘No offence, sir,’ said Sergeant Nairn, ‘but think we could get a move on? I’d kinda like to get out of here before the natives go apeshit.’

‘Right. Sorry…’ Will cleared his throat. ‘Good point.’

He forced his feet to move again, following DS Jo Cameron down the broken escalator into the depths of the building.

‘You know,’ she said as they passed the fifty-first floor, ‘you seem a bit tense.’

‘Really.’ Will frowned in the darkness. It stank of mildew in here, stale air, and something sickly sweet and floral-not quite covering up the sour background smell of damp carpet.

‘Yeah, ever since George showed you those brain scans you look like you’re holding a hand grenade between the cheeks of your bum. I’ve visited Sherman House dozens of times, it’s not as bad as you think any more. Honestly.’

Will turned the next corner-looking out at another identical corridor. ‘Think we could just focus on the job in hand?’

‘If you don’t want to talk about it, just say so.’

‘I don’t want to talk about it.’

She shrugged. ‘Suit yourself.’

It seemed to take forever to work their way down to the forty-seventh floor.

Will hadn’t seen a single living soul since they’d arrived on the roof; nearly sixty thousand people lived in Sherman House and there was no sign of any of them. Like the place wasn’t creepy enough.

DS Cameron stepped off the escalator ramp, took one look at the shabby hallway, and summed up all that human misery and squalor in five words:

‘Can you smell cat pee?’

Stein and Beaton were hauling their scanning equipment along the threadbare carpet, swearing their way towards the late Allan Brown’s last known address. Past them Will could just make out the faint glimmer of a Whomper’s telltales: that would be Private Wright, standing guard. The sinister shape of Private Dickson and her Bull Thrummer lurked down the other end, cordoning off the whole area. Anyone wanting to cause trouble would end up missing a large part of their anatomy.