It wasn’t much more than a couple of miles from the West End, as the crow flies, and he decided the walk would do him good. He had always loved walking in cities, and London was a great place for it. He had been cheated out of Paris, so he would have to make the best of where he was. If he set off now, he realized, he would probably arrive around lunchtime. If he got Louisa’s address from Ruth, he would go there in the early evening, between six or seven, which he had always found was a good time to catch people in. That should also leave him plenty of time to meet Sandra at eight in Camden Town.

A cool wind skipped off the murky river and whistled around his ears as he crossed Lambeth Bridge. He glanced back. Shafts of light lanced through the clouds and lit on the Houses of Parliament. It was odd, Banks thought, but when you visit a place you used to live in for a long time, you see it differently; you become more like a tourist in your own land. He would probably never have even noticed Big Ben or the Houses of Parliament in the days when he had lived there. Even now, his copper’s eye was more tuned to the two shifty-looking skinheads across the road, who seemed to be following a couple of Japanese tourists, than it was to the beauty of the London architecture.

It was pushing twelve-thirty when Banks got to Ruth’s street just off Kennington Road. The brick terrace houses were four stories high and so narrow they seemed pressed together like a mouthful of bad teeth. Here and there someone had added a lick of bright paint to a window frame, or put out a few potted plants in the bay window.

The name “R. A. Walker” appeared by the third-floor bell, a dead giveaway that the occupant was a woman. Banks pressed and heard it ring way up in the distance. He waited, but nobody came. Then he tried again. Still nothing. After standing on the doorstep for a few minutes, he gave up. He hadn’t wanted to phone ahead and tip her off that he was coming – finding that surprise often worked best in situations like this – so he had been prepared to wait.

Banks decided to have his lunch and call back in an hour or so. If she wasn’t in then, he’d think of a new plan. He found a serviceable pub on the Main Street and enjoyed a pint as he finished reading the newspaper. A few regulars stood at the bar, and a younger crowd was gathered around the video machines. One man, wearing a tartan cap, kept nipping around the corner to the betting shop and coming back to tell everyone in a loud voice how much he’d lost and how the horse he’d backed belonged in the glue factory. Everyone laughed indulgently. Nobody paid Banks any mind, which was just the way he liked it. He glanced over the menu and settled finally on a chicken pot pie. It would have suited Annie Cabbot just fine, Banks thought as he searched in vain among peas and carrots for the meat; Annie was a vegetarian.

A short while later, he stood on Ruth Walker’s doorstep again and gave her bell a long push. This time, he was rewarded by a wary voice over the intercom.

“Who is it?”

“I’ve come about Louisa,” Banks said. “Louisa Gamine.”

“Louisa? What about her? She’s not here.”

“I need to talk to you.”

There was a long pause – so long that Banks thought Ruth had hung up the intercom on him – then the voice said, “Come up. Top floor.” A buzzer went off and Banks pushed the front door open.

The stairs were carpeted, though the fabric had worn thin in places and the pattern was hard to make out. A variety of cooking smells assailed Banks as he climbed the narrow staircase: a hint of curry, garlic, tomato sauce. When he got to the top, there was only one door. It opened almost immediately when he knocked, and a young woman looked at him through narrowed eyes. After she had studied him for a while, she opened the door and let him in.

The best Banks could say of Ruth Walker was that she was plain. It was a cruel and unfair description, he knew, but it was true. Ruth was the kind of girl who, in his adolescence, always went around with an attractive friend, the one you really wanted. The Ruths of this world you usually tried to palm off on your friend. There was nothing distinguishing about her except, perhaps, the intelligence perceptible in her disconcerting and restless gray eyes. Already she seemed to have a permanent frown etched in her forehead.

She was dressed simply in baggy jeans and a T-shirt commemorating an old Oasis tour. Her hair, dyed black, gelled and cut spiky, didn’t suit her round face at all. Nor did the collection of rings and studs through the crescent edges of her ears. Her complexion looked dry as parchment, and she still suffered the ravages of acne.

The flat was spacious, with a high ceiling and one of those Chinese-style globe lampshades over the bulb. Bookshelves stood propped on bricks against one wall, not much on them, apart from tattered paperbacks and a few software manuals, and a computer stood on the desk under the window. A sheepskin rug covered part of the hardwood floor, and various quilts and patterned coverlets hung over the secondhand three-piece suite. It was a comfortable room; Ruth Walker, Banks had to admit, had made a nice home for herself.

“I don’t usually let strangers in,” she said.

“A good policy.”

“But you mentioned Louisa. You’re not one of her new friends, are you?”

“No, I’m not. You don’t like them?”

“I can take them or leave them.” Ruth sniffed and reached for a packet of Embassy Regal resting on the coffee table. “Bad habit I picked up in university. Want a cup of tea?”

“Please.” It would set them at ease, Banks thought, create the right atmosphere for the sort of informal chat he wanted. Ruth put the cigarettes down without lighting one and walked into the kitchen. She had a slight limp. Not enough to slow her down, but noticeable if you looked closely enough. Banks looked at the book titles: Maeve Binchy, Rosamunde Pilcher, Catherine Cookson. A few CDs lay scattered beside the stereo, but Banks hadn’t heard of most of the groups, except for the Manic Street Preachers, Sheryl Crow, Beth Orton, Radiohead and P.J. Harvey. Still, Ruth probably hadn’t heard of Arnold Bax or Gerald Finzi, either.

When Ruth came back with the tea and sat opposite him, she still seemed to be checking him out, probing him with those suspicious gray eyes of hers. “Louisa,” she said, when she had finally lit her cigarette. “What about her?”

“I’m looking for her. Do you know where she is?”

“Why?”

“Does it matter?”

“It might. You could be out to do her harm.”

“I’m not.”

“What do you want with her, then?”

Banks paused. Might as well do it again; after all, he’d got this far on a lie, and it was beginning to fit so well he almost believed it himself, even though he had never met Emily Riddle. “I’m her father,” he said. “I just want to talk to her.”

Ruth just stared at him a moment, her eyes narrowing. “I don’t think so.” She shook her head.

“You don’t think what?”

“That you’re Louisa’s father.”

“Why not?”

“He wouldn’t come looking for her, for a start.”

“I love my daughter,” Banks said, which at least was true.

“No. You don’t understand. I saw a photo. A family photo she had with the rest of her things. There’s no point lying. I know it wasn’t you.”

Banks paused, stunned as much by Emily’s taking a family photo as by Ruth’s immediate uncovering of his little deception. Time for a change of tack. “Okay,” he said. “I’m not her father. But he asked me to look for her, to try to find her and ask her if she’d talk to him.”

“Why didn’t he come himself?”

“He’s afraid that if she knows he’s looking for her she’ll make herself even more scarce.”

“He’s got that one right,” said Ruth. “Look, why should I tell you anything? Louisa left home of her own free will, and she was of legal age. She came down here to live her own life away from her parents. Why should I mess things up for her?”