Tuesday 10th October

By four o'clock DI Costello was walking along Byres Road, her hands buried deep in her pockets, collar up to protect her from the sudden onslaught of rain. She was heading for Superdrug to buy some shampoo and deodorant. She had been using soap on her hair for the last fortnight and spraying a cheap perfume called Kabana over herself in any breaks in court proceedings. It made her smell as though she had just cleaned out the toilets, but it was worth it to be there.

To hear the word.

Guilty.

The look on Bernadette Kissel's face was worth it.

Now DI Costello wanted to celebrate, but only after spending an hour in a hot shower, washing the stink of the Kissel case off her skin, scrubbing those images from her eyes. She wondered if DCI Anderson had been following the case; it would have been difficult for him to avoid it. One day last week, she couldn't remember which day – the trial seemed to go on for ever – her face had been on the front page, sharp focus, her frown making the scar on her forehead pucker. Beside her there was a picture of Professor Jack O'Hare, or 'John' as they had called him. Unfortunate black and white pictures of them looking tired and ineffectual, taken as they left the court, one word underlining the images: MISTAKES.

She had been furious but the professor hadn't minded at all. Of course, mistakes had been made. But not by them. The pathologist had taken it all with the finality of one who spends most of his time with the dead.

Costello, hurrying to get out of the sudden onslaught of rain, paused under the emerald green and gold awning of La Vita Spuntini, her eye attracted by a familiar jacket with a small herringbone pattern. She recognized the square head, the salt and pepper hair, the white shirt with ironed blade creases down the sleeves. She recognized the back of his neck.

Archie Walker, Chief Procurator Fiscal and her ... well, whatever he was. They were too old to be 'friends with benefits'. He sat with his back to the window, studying a few pages of A4 paper. She waited for him to remove the staple, flatten the papers out to line them up correctly. Finger and thumb pinched the corners, like an entomologist selecting some rare species.

She was about to tap on the window when she noticed there were two glasses on the table, both poured. White wine. Archie looked up and smiled in the direction of the small, tanned brunette pulling down on the cuffs of the cream blouse that hung loose over her black skirt. She appeared to have been to the loo and had rolled up her sleeves to give her hands a thorough wash. Somebody who routinely touched something unpleasant and had learned to wash their hands scrupulously?

Pathologist? A lab technician?

But Costello didn't recognize her.

Archie slid his papers from the table back into his briefcase. He locked the case, spinning the digits. The brunette moved an empty glass from another table and set it in front of her, placing both full wine glasses in front of him. Had he ordered wine? It was lunchtime and Archie never drank this early. Now the brunette was moving all three glasses, so she could get closer to him across the narrow table.

These two knew each other well. They were very cosy.

And Costello had no idea who the woman was.

She was talking now, this brunette. Friendly, laughing slightly. It didn't look like two lawyers discussing a case, ready to take corners and argue the burden of proof.

The brunette was younger than Archie, in her thirties? Minimal make-up, a very good suit and a blouse that looked rather loose as if she had lost weight and classic high-heeled black shoes. Her long dark brown hair was perfectly curled into a French roll, a few loose strands falling over her face to soften the look.

Probably another fiscal, somebody from his office. Costello raised her hand to tap the rain-spattered glass, as the woman threw her head back to laugh.

When had Archie ever said anything that funny?

The brunette glanced out the window and caught Costello's eye, her gaze passing over her as if she was invisible. No recognition. Nothing.

Costello lowered her hand and tilted her head to look at her own reflection, red-rimmed, baggy eyes and spikey, wet scarecrow hair. She noticed her own fingernails, rough and bitten, as the brunette reached her manicured hand out to lay it gently on Archie's wrist. He leaned forward, looking as though he was whispering to her across the table. Then she laughed again. She had a long feminine throat, a finely crafted silver butterfly hung round it, the delicate chain attached to each upper wing.

Had Archie just kissed the back of her hand?

Bastard. Costello walked away, across the road, stepping into the puddles. As she splashed along Byres Road towards Superdrug, an Asian woman with a long, purple-patterned dirndl skirt and a washed out baggy, blue woolly jacket approached her, hood up against the rain. Under her arm was a huge Lidl bag bulging like a balloon. Costello noticed the rainwater running out the side of the woman's crocs. She had her arm up, palm out as if to catch hold of her as she passed.

'I've no spare change,' snapped Costello, automatically and sidestepped. She was not in a mood to be generous.

At five p.m. Roberta closed the door of the Duster and eased out the drive, phone on hands-free in case James had news about the new job.

She pulled out of Acacia Crescent heading down towards the Avenue. They could take a wee drive along the twisting farm roads around Waterside. The smooth rocking of the car had put Sholto to sleep at half two this morning and again at half five. God, she was tired, the back of her eyelids felt like sandpaper. The cold outside chilled her tired, weary bones in a way that no long soak in a hot bath could ease. She was in the permanent winter of a land somewhere beyond exhaustion.

Nobody told her it would be like this. She had spent hours at the hairdressers when she was pregnant, reading the celebrity magazines and she'd imagined she would be like Angelina Jolie. Have a baby, go back to work, get a good night's sleep, the house would stay clean, her figure would snap straight back into shape and bits of her anatomy would stop leaking. Nobody had told her that babies stay awake twenty-four-seven, and that for the first six weeks she would have difficulty remembering her own name. And there were a lot more hours in the day, long, long hours where the crying never stopped. And yet she never had enough time to do anything.

'Why don't you just sleep, you wee pig,' she asked. Her baby son looked comfortable enough in his new blanket, still clean enough to see the fluffy cream lambs round the bottom.

Sholto looked at her with big blue, tearful eyes, and for one short moment he fell silent, as if he was chewing the idea over, considering the concept in his tiny mind. He rejected it and started wailing like a siren sounding a red alert.

When the mobile rang, Roberta pulled over, put the handbrake on and stepped out the car to stand in the road, in the rain, so she could hear her husband properly.

James's voice came through loud and clear. 'How do you fancy a glass of bubbly tonight?'

'You got the job?'

'I did and the pay rise means you don't need to rush back to work.'

She pulled up her hood. 'And how do we celebrate with the noise of the jumbo jet on a test flight in the room with us?'

'A drink might help you sleep.'

'I don't need any bloody help sleeping. It's him that doesn't sleep. I need help to stay awake.'

'OK, maybe if you calm down, he might relax better and stop screaming.'

Roberta felt like screaming. It was OK for him, driving to work in a nice silent car, staying late at the office then going to the pub, engaging with grown-ups who talk rather than gurgle and who smell of aftershave rather than Nappy San.

'Calm down.' James repeated. 'Go to Barry's and buy a nice bottle of bubbly, push the boat out, thirty or forty quid. Go home and stick it in the fridge and I'll pick up a nice takeaway.'

'OK. Congratulations,' she muttered and climbed back into the ear-splitting interior. She shoved a Kleenex in each of her ears and drove on.

Ten minutes later, she pulled up in the inshot outside Barry's. The sky was darkening, the temperature had dropped. As she removed her makeshift earplugs, she looked at Sholto, and his mouth was closed.

In the car there was only the quiet rattle of the rain on the roof, the gentle rumble of the engine, and the easy rasp of Sholto's breathing. Then the engine cut off.

He had stopped crying.

Actually stopped crying.

His blue eyes widened and looked up at hers, beguiling in their threat to start again.

She waited.

He remained quiet.

She reached to undo the seat belt and stopped as he opened his mouth. Moving him now might not be a good idea.

She looked into the shop window. Barry was visible through the row of hams hanging across the window, chatting animatedly as he wrapped something small in paper and placed it in a plastic bag. The queue was short. She caught his eye and waved at him. He waved back, recognizing the car, if not the driver. She watched him as he turned and said something to a customer at the back of the shop, pointing out to the street.

Slowly and gently, she slid out the driver's seat and eased the car door over, without closing it properly to avoid any harsh clicks. She dashed into the shop, scanning the shelves of sparkly, then making her way to the fridge at the back. This was going to be her first drink for a year. She could feel her taste buds tingling already.

Barry asked her how she was doing as she handed over the bottle of chilled Tattinger. He wrapped it slowly in tissue paper and tucked the ends in neatly. Roberta looked out at the car, checking that it was OK and that the monster was not awake and screaming.

'James got the job?' Barry asked.

'How did you guess?'

'You look happy. You had any sleep yet?' Barry took her credit card and wandered to the machine at the counter.

'Nope but he's stopped crying now so I live in hope.' She followed him, giving the car a glance over her shoulder. 'Last night he slept for a whole hour and a half. Imagine!' She listened to Barry telling her that his middle boy had been like that, but had grown out of it eventually.

'How long was eventually?' Roberta asked, hopefully.

Barry handed her the machine for her pin number. 'Well, he started sleeping then sleep walking, then not sleeping again, then coming into our bed every two minutes, then teething and screaming the house down. In fact, he has been a right pain in the arse from the moment he was born.'

Roberta played along, enjoying this adult exchange, being witty, using her brain. Something beyond 'The Wheels On The Bus'. 'And how old is he now?'

'Twenty-six. He still lies in bed all day, playing his Xbox. Still talks crap. But you've got to love them.'

Roberta smiled, took the bottle and the credit card in its little blanket of receipt.

She walked out the shop, busy holding the bottle, slipping the credit card safely in her purse, closing the clasp, watching her step on the wet floor, before she looked up.

The Duster was gone.

DCI Colin Anderson listened to Brenda's voicemail but didn't leave another message. It was after five, she was normally home with Peter by now, giving their son his tea. Reluctantly, he joined the queue at the water cooler outside the main investigation suite. His meeting at West End Central was running late, so he may as well stay on and work the rest of the evening. He had nothing much to go home to. He eavesdropped on one of his new colleagues, Steve, talking about his vengeful ex-wife, his money-grabbing present wife and the wondrous tottie he had his sights on for wife number three. Anderson and Brenda – he couldn't even refer to her as an 'estranged wife' – had a very good relationship. In Steve's opinion that was due to the little matter of Anderson inheriting a million-pound house, despite him arguing, truthfully, that it was the twenty-year marriage and two kids that kept them close.

And Steve had laughed.

Was it him or were all cops complete dicks these days?

Bruce, Stevie's partner in crime, took out his mobile and began scrolling. 'The jury in the Kissel case are back. Guilty on all counts.'

'Was there ever a doubt? That kid was dead in the flat for six months before anybody noticed. I'm surprised they are not asking for the death penalty to be reinstated.'

'And your old pal was front page news, did you see that? The old woman?'

Anderson tried to make the connection in his mind. He had seen the headlines. It was a long time before the penny dropped. 'Costello, you mean, my old DI?' he said, well aware that he hadn't spoken to her about it, even though the case had been all over the media. Not so long ago, she would have been his first call. He looked at his watch, she'd be off duty by now. Maybe better to leave it.

'Word from Govan is that she made mistakes, her and that old pathologist. He should be retired by now anyway.' Stevie offered his valued opinion. 'There's a nice new pathologist over at the QE, little blonde, Welsh. Got an arse that could make a vicar kick a stained-glass window.'

Bruce chipped in. 'Costello's been drifting for a while. She must have been a dead weight in your career, Colin. I mean you were really going places. At one point. Is she retiring now?'

Retiring? Costello was only a few years younger than him. It was a chilling thought. Anderson looked at his phone, scrolling, pretending that he was reading the news updates on the Kissel case. God, in the old days they had shared everything, sat on surveillance in frozen cars for bum-achingly tedious hours, sipping tea from a flask and eating cold chips. He knew her so well he could choose her as his specialist subject on Mastermind. She was one of the few women he knew who was happy to sit in silence. Why had he not phoned her? Was he jealous that she was still out there doing the job while he was stuck in here with the Versace twins?

And did they see him as they saw her, old with his career well and truly behind him?

Cold case units had so many different names to mask the reality of the bureaucratic game of pass the parcel. They opened files, a quick check to see if any advancement in forensics might help or if there was any nicely preserved, uncontaminated material to test. There rarely was. So the file was closed again and left for the next review.

He was going to be the sixth unwanted cop to review the Gillian Witherspoon case. What was he supposed to do? Go out and interview Gillian, so she knew she wasn't forgotten? 'Under constant review' sounded like good policing to some but to others making contact with the victim every three years only dragged up painful memories that prevented them from moving on.

He looked at the picture inside the front page of the file, a pleasant, totally unremarkable woman except that on the 15th of March 1996, Gillian, a young, busy mum of two, had nipped out to her local shop for a pint of milk at night after watching the ten o'clock news, full of the horror of the Dunblane massacre. She had pulled her coat over her PJs, slipped on her trainers and picked up her purse to walk down to the main road and the garage shop. It was well covered by CCTV, it was an unseasonably warm night, the area was well lit. Everybody knew everybody. Nobody saw anything.

But somebody had been watching.

She was found behind the bins, bleeding badly. She couldn't remember what she saw, or heard, or smelled, or tasted, only that she had been aware of somebody.

End of.

As the rage of Thomas Hamilton unfolded, Gillian got lost in the later pages of the press. She had been divorced in 1998. Anti-depressants followed. Not an unfamiliar story.

'Looks like we are reconvening.' Stevie crushed his plastic cup in his fist and tossed it into the non-recyclable. 'Yeeeees,' he said, 'got it in one.'

'You've still got the moves,' agreed Bruce, and they high fived each other. Anderson walked quickly away before they started French kissing.

Roberta stopped dead, the world stopped with her. For a stupid moment, she turned to glance behind her, thinking she had come out a different door of the shop. She looked up and down the street, but the Duster was gone.

The car parking space was empty.

The baby was gone.

Baby Sholto was gone.

She dropped the bottle. It exploded onto the concrete, feathering the streets with champagne.

She turned around to see if anybody was about. 'Did you see? Did anybody see? Where is my son, where is my baby?' She knew that the words were coming out her mouth but they didn't sound right. She was merely making noises.

Grabbing a pensioner in a grey raincoat, she screamed in her face, 'Sholto? Sholto? Sholto! Where is the blue Duster? There was a blue Duster parked right there.' She pointed, then grabbed the old lady again, this time by the shoulders, and began to shake her. 'Did you see them? Who drove my car away?'

Then strong hands were removing hers from the damp grey raincoat. Barry was out the shop, shouting at his assistants, sending one to run up the street, the other down. The Duster couldn't have gone far.