As the liquid trickles into her veins, the dull ache at the back of her head begins to lift, the tightness in her throat lessens, her stomach stops growling-even though she hasn’t actually eaten anything. She closes her eyes and drifts for a moment. Happy.

Grabbing another pack from the pile, she clambers up a wall of toilet paper and makes a little nest for herself beneath the coolant fan. Surrounded by a protective wall of extra-soft quilted tissue she slips the new pack into place and settles down to sleep. For the first time in six years, she is comfortable. Safe.

There are many things that still need to be done, but for now she is content just to rest.

‘So this is where you’ve been hiding.’

Will peered out from beneath his VR headset. Lieutenant Brand was lounging against the reconstruction suite wall, wearing another grey jumpsuit-urban concrete-coloured camouflage. Only this time she didn’t have her bra on show.

‘I’m not hiding.’

‘Bollocks you’re not. You’ve been down here all morning, looking like something off the History Channel. Headset and gloves: you’re such a sodding luddite. Why can’t you get a jackpoint like normal people?’

Will stuck two fingers up at her.

She shrugged, sighed, then pointed at the room’s terminal. The chunky evidence cartridge with the scans from flat 47122 was plugged into it, chugging and creaking as the computer interpreted the data into three dimensions. ‘That your mystery room?’

‘Want to take a look and tell me what you think?’

She unspooled a lead from the wall; breathed on the little gold connector; polished it against her sleeve; checked it was clean; then felt for the socket in the back of her head with her other hand, freezing just before she clicked the jack into place. ‘You spring for lunch afterwards?’

Will nodded. ‘Deal.’

He was as good as his word. Thirty minutes later they were sitting in the cafeteria, eating stovies. They’d been over the deep scan readings, the narrow band and the subsonics; they’d even run simulations to track the order of events. None of which explained why flat 47-122 looked so different before and after.

‘So,’ he speared a little chunk of cloned lamb from the mound of stodgy potato and onion on his plate, ‘what do you think?’

‘We have to go back. If that place was redecorated the way you said it was-’

‘And it was.’

‘Then something frinky’s going on.’

He looked at her. ‘“Frinky”?’

‘Not my fault you’re stuck in a time warp.’

‘Yes, well…’ He loaded up another forkful. ‘Sherman House is off limits: the Fairy Princess vetoed all Network intrusions for at least a fortnight. We go back in there with another pickup team we’ll start a riot.’

‘Then we don’t take a pickup team.’ Emily cast a quick glance around the crowded canteen, then dropped her voice to a whisper. ‘She said no Network intrusion: didn’t say anything about you and me visiting a sick friend who just happens to live there.’

‘A sick friend?’

‘Trust me, if we don’t get caught we won’t have to go into any details. We can hop a public shuttle from the Pavilion.’ She waggled her knife at him, speaking with her mouth full. ‘Better get a change of clothes: you’ll stick out like a sore thumb in that monkey suit. We’ll do it this evening, about half five?’

‘It’s a date.’

Emily raised an eyebrow, but didn’t say a word.

A shadow fell across the table and Will turned to see DS Cameron in a canary yellow suit, Brian lumbering after her. ‘Ah, here you are,’ she said, eyes sparkling in the overhead light. ‘Guess what: we’ve identified that halfhead who went missing from the Sherman House toilets!’

‘You got Services to talk?’ Will was impressed; he’d forgotten all about the abandoned mop and wheely-bucket. ‘Who was it?’

‘And,’ a big smile spread across her face, ‘we’ve got a match on the MO used on our murder victim. You’re not going to believe-’

‘Wheesht!’ Brian cut her off. He sank down into the chair next to Will. ‘The missin’ halfhead was S H dash O slash D dash one zero two eight six. The dead body in the bog was killed the same way as twenty-seven of her victims-’

‘Oh God…’ The fork fell from Will’s hand, skittering across the tabletop, spreading little droplets of pickled beetroot juice. Like a blood spatter pattern. ‘She’s still out there…’

Brian shook his head. ‘She’s no’ anywhere Will: she’s dead. The Roadhugger takin’ her back to the depot went over the Connelly Memorial Flyover yesterday evenin’. Fell fifty foot onto the back of a bus. No survivors.’ He paused. ‘They’ve got what’s left of her on a slab down the city mortuary, if you want to see her?’

Lieutenant Brand reached across the table and took hold of Will’s hand. ‘You OK?’

DS Cameron stuck a datapad on the table, crime scene photos from the Sherman House toilets fading in and out in a macabre slideshow. ‘It’s a classic copycat killing. Perp finds out who she is, then stalks her for a couple of weeks, working on the fantasy, waiting for an opportunity to perform. Probably made her watch as he butchered Allan Brown.’

It didn’t seem to bother her that no one else was celebrating. ‘Doing a background search on the Roadhugger’s crew now. I’m betting one of them has a record of psychological problems. You know: got the job so he could work with killers and rapists, waiting for his chance to be just like them.’

Will lurched to his feet. The room was beginning to pulse. Hot. Hard to breathe. Mouth coated in grease and the taste of meat. Bile.

‘Need to get some air…’

‘Feeling any better?’ Lieutenant Brand settled back against the handrail.

Will straightened up, wiped a hand across his mouth, shrugged. Mouth rank with the bitter taste of vomit. ‘Not really.’

The landing bays were empty, no one about on the roof of Network Headquarters to see him spatter a half portion of stovies all over the walkway. Brian had stayed behind, keeping DS Cameron busy and out of the way.

It was stifling up here, the afternoon pressing down on him like a steam iron. The layer of clouds above the city was getting thicker, turning ominous and dark. Threatening what everyone so desperately wanted: an end to the terrible heat.

He clutched the rail and stared out into the distance, wondering if he was going to be sick again.

A gentle hand brushed his shoulders. ‘You want to talk about it?’

‘No.’ He sighed. Looked out across the sweltering city. ‘Haven’t thought about her in years…Well, except for anniversaries, birthdays, Christmas, you know-things like that.’ He ran a finger along the thin band of pale skin where his wedding ring used to be. ‘Funny isn’t it? How…’ He stopped. Cleared his throat. ‘When Brian said the MO matched…I know she’s been cleaning toilets and sweeping the streets for the last six years, but she was a halfhead. You know what I mean? She wasn’t really alive anymore. And then suddenly bang! Back to square one.’

They stood in silence for a while, leaning on the rail, not really looking at the view.

And then Will straightened up. ‘I want to see her.’

‘Good idea-stinks of puke up here anyway.’ Emily linked arms with him and steered him towards the lifts. ‘How about we knock off early? Get smashed at one of those stuck-up freezy joints. Embarrass a few of the idle rich with our rough, working-man’s banter.’

‘Thought we were going to see that sick friend of yours.’

‘No chance.’ Emily hit the button for the Network’s shuttle station. ‘You need to let off steam, and until you do, you’re dangerous. Tonight we get plastered. Tomorrow we go visiting.’

The chief pathologist at Glasgow Royal Infirmary checked their IDs again, even though the security guards had done it three times already on their way down here. Tall, thin, with a hooked nose, and mane of fading ginger hair, he was straight out of a Brothers Grimm fairytale.