`Have you ever heard of something called the Rat Line?’ Rebus had asked at their first meeting.

`Of course,' Joseph Lintz had said. `But I never had anything to do with it.’

Lintz: in the drawing-room of his Heriot Row home. An elegant four-storey Georgian edifice. A huge house for a man who'd never married. Rebus had said as much. Lintz had merely shrugged, as was his privilege. Where had the money come from? `I've worked hard, Inspector.’

Maybe so, but Lintz had purchased the house in the late-1950s on a lecturer's salary. A colleague from the time had told Rebus everyone in the department suspected Lintz of having a private income. Lintz denied this.

`Houses were cheaper back then, Inspector. The fashion was for country properties and bungalows.’

Joseph Lintz: barely five foot tall, bespectacled. Parchment hands with liver spots. One wrist sported a pre-war Ingersoll watch. Glass fronted bookcases lining his drawing-room. Charcoal-coloured suits. An elegant way about him, almost feminine: the way he lifted a cup to his lips; the way he flicked specks from his trousers.

`I don't blame the Jews,' he'd said. `They'd implicate everyone if they could. They want the whole world feeling guilty. Maybe they're right.’

`In what way, sir?’

`Don't we all have little secrets, things we're ashamed of?’

Lintz had smiled. `You're playing their game, and you don't even know it.’

Rebus had pressed on. `The two names are very similar, aren't they? Lintz, Linzstek.’

`Naturally, or they'd have absolutely no grounds for their accusations. Think, Inspector: wouldn't I have changed my name more radically? Do you credit me with a modicum of intelligence?’

`More than a modicum.’

Framed diplomas on the walls, honorary degrees, photos taken with university chancellors, politicians. When the Farmer had learned a little more about Joseph Lintz, he'd cautioned Rebus to `ca' canny'. Lintz was a patron of the arts opera, museums, galleries – and a great giver to charities. He was a man with friends. But also a solitary man, someone who was happiest when tending graves in Warriston Cemetery. Dark bags under his eyes, pushing down upon the angular cheeks. Did he sleep well? `Like a lamb, Inspector.’

Another smile. `Of the sacrificial kind. You know, I don't blame you, you're only doing your job.’

`You seem to have no end of forgiveness, Mr Lintz.’

A careful shrug. `Do you know Blake's words, Inspector? "And through all eternity/ I forgive you, you forgive me.” I'm not so sure I can forgive the media.’ This last word voiced with a distaste which manifested itself as a twist of facial muscles.

`Is that why you've set your lawyer on them?’

‘"Set" makes me sound like a hunter, Inspector. This is a newspaper, with a team of expensive lawyers at its beck and call. Can an individual hope to win against such odds?’

`Then why bother trying?’

Lintz thumped both arms of his chair with clenched fists. `For the principle, man!' Such outbursts were rare and shortlived, but Rebus had experienced enough of them to know that Lintz had a temper…

`Hello?’ Kirstin Mede said, angling her head to catch his gaze.

`What?’

She smiled. `You were miles away.’

`Just across town,' he replied.

She pointed to the papers. `I'll leave these here, okay? If you've any questions…’

`Great, thanks.’

Rebus got to his feet.

`It's okay, I know my way out.’

But Rebus was insistent. `Sorry, I'm a bit…’

He waved his hands around his head.

`As I said, it gets to you after a while.’

As they walked back through the CID office, Rebus could feel eyes following them. Bill Pryde came up, preening, wanting to be introduced. He had curly fair hair and thick blond eyelashes, his nose large and freckled, mouth small and topped with a ginger moustache – a fashion accessory he could well afford to lose.

`A pleasure,' he said, taking Kirstin Mede's hand. Then, to Rebus: `Makes me wish we'd swopped.’

Pryde was working on the Mr Taystee case: an ice-cream man found dead in his van. Engine left running in a lock-up, looking initially like suicide.

Rebus steered Kirstin Mede past Pryde, kept them moving. He wanted to ask her out. He knew she wasn't married, but thought there might be a boyfriend in the frame. Rebus was thinking: what would she like to eat – French or Italian? She spoke both those languages. Maybe stick to something neutral: Indian or Chinese. Maybe she was vegetarian. Maybe she didn't like restaurants. A drink then? But Rebus didn't drink these days.

`… So what do you think?’

Rebus started. Kirstin Mede had asked him something.

`Sorry?’

She laughed, realising he hadn't been listening. He began to apologise, but she shook it off. `I know,' she said, `you're a bit…’

And she waved her hands around her head. He smiled. They'd stopped walking. They were facing one another. Her briefcase was tucked under one arm. It was the moment to ask her for a date, any kind of date – let her choose.

`What's that?’ she said suddenly. It was a shriek, Rebus had heard it, too. It had come from behind the door nearest them, the door to the women's toilets. They heard it again. This time it was followed by some words they understood.

`Help me, somebody!' Rebus pushed open the door and ran in. A WPC was pushing at a cubicle door, trying to force it with her shoulder. From behind the door, Rebus could hear choking noises.

`What is it?’ he said.

`Picked her up twenty minutes ago, she said she needed the loo.’

The policewoman's cheeks wore a flush of anger and embarrassment.

Rebus grabbed the top of the door and hauled himself up, peering over and down on to a figure seated on the pan. The woman there was young, heavily made-up. She sat with her back against the cistern, so that she was staring up at him, but glassily. And her hands were busy. They were busy pulling a streamer of toilet-paper from the roll, stuffing it into her mouth.

`She's gagging,' Rebus said, sliding back down. `Stand back'. He shouldered the door, tried again. Stood back and hit the lock with the heel of his shoe. The door flew open, catching the seated woman on the knees. He pushed his way in. Her face was turning purple.

`Grab her hands,' he told the WPC. Then he started pulling the stream of white paper from her mouth, feeling like nothing so much as a cheap stage-show magician. There seemed to be half a roll in there, and as Rebus caught the WPC's eye, both of them let out a near-involuntary laugh. The woman had stopped struggling. Her hair was mousy brown, lank and greasy. She wore a black skiing jacket and a tight black skirt. Her bare legs were mottled pink, bruising at one knee where the door had connected. Her bright red lipstick was coming off on Rebus's fingers. She had been crying, was crying still. Rebus, feeling guilty about the sudden laughter, crouched down so that he could look into her makeup-streaked eyes. She blinked, then held his gaze, coughing as the last of the paper was extracted.

`She's foreign,' the policewoman was explaining. `Doesn't seem to speak English.’

`So how come she told you she needed the toilet?’

`There are ways, aren't there?’

`Where did you find her?’

`Down the Pleasance, brazen as you like.’

`That's a new patch on me.’

`Me, too.’

`Nobody with her?’

`Not that I saw.’

Rebus took the woman's hands. He was still crouching in front of her, aware of her knees brushing his chest.

`Are you all right?’

She just blinked. He made his face show polite concern. `Okay now?’

She nodded slightly. `Okay,' she said, her voice husky. Rebus felt her fingers. They were cold. He was thinking: junkie? A lot of the working girls were. But he'd never come across one who couldn't speak English. Then he turned her hands, saw her wrists. Recent zigzag scar tissue. She didn't resist as he pushed up one sleeve of her jacket. The arm was a mass of similar inflictions.