Suddenly Graham realised - with a small, disquieting feeling in his stomach - that they were standing right outside a place which always made him feel apprehensive.

It was only a small picture-framing shop which sold prints and posters and more-tasteful-than-average lampshades, but it was the name which held unpleasant associations for Graham: Stocks. That name chilled him.

Stock was his rival, the great threat, the cloud hanging over him and Sara. Stock the biker, the macho black-leathered never-properly-seen image of Nemesis. (He had looked up the name in the London telephone directory; there were one-and-a-half columns of them; enough for quite a few coincidences, even in a city of six-and-a-half million people.)

Slater was saying, "- to do with it?"

"It just occurred to me," Graham said defensively. He wished now he hadn't decided to tease Slater.

"You haven't listened to a word I've said," Slater gasped. Graham nodded to indicate they should keep on walking.

"Of course I have," he said. They passed Terry's fruitstall next, with its smell of fresh strawberries, then a chemist's. They were at the junction of Clerkenwell Road and Rosebery Avenue. By the side of Gray's Inn Buildings, which led on up the Avenue, some tall green wooden hoardings jutted out over part of the street and pavement, shielding some roadworks. Graham and Slater walked down the narrow alley formed by the seedy, decaying stonework and the painted wood; Graham saw the grimy glass of cracked windows; fading political posters flapped in a slight breeze.

"But don't you think it's a laugh?" Slater said, trying to edge round Graham to peer into his face. Graham avoided his friend's eyes. He wondered if Slater intended to walk the whole way with him, or whether he was only going as far as the Air Gallery, now only just across the street, where he sometimes went in the afternoons. Graham didn't mind Slater knowing about Sara - he had introduced them to each other, after all - but he wanted to keep this day private. Besides, he got embarrassed at the stares people gave Slater, even if Slater himself didn't seem to notice. The least he could do, Graham thought, was take off that ridiculous tartan cap.