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...