‘I don’t think you can help me,’ Siobhan admitted, looking around. She was resisting the urge to scratch herself. ‘I’m interested in something slightly more high-tech.’

He bristled at this. ‘What do you mean?’

‘Role-playing by computer.’

‘Interactive?’ His eyes widened. She nodded and he checked his watch again, then shuffled past her to the door and locked it. She went on the defensive, but he merely shuffled past her again on his way to the far door. ‘Down here,’ he said, and Siobhan, feeling a bit like Alice at the mouth of the tunnel, eventually followed.

Down four or five steps, she came into a dank, windowless room, only partially lit. There were boxes piled high – more games and accessories, she guessed – plus a sink with kettle and mugs on the draining-board. But on a table in one corner sat what looked like a state-of-the-art computer, its large screen as thin as a laptop’s. She asked her guide what his name was.

‘Gandalf,’ he blithely replied.

‘I meant your real name.’

‘I know you did. But in here, that is my real name.’ He sat down at the computer and started work, talking as he moved the mouse. It took her a moment to realise that the mouse was cordless.

‘There are lots of games on the Net,’ he was saying. ‘You join a group of people to fight either against the program or against other teams. There are leagues.’ He tapped the screen. ‘See? This is a Doom league.’ He glanced at her. ‘You know what Doom is?’

‘A computer game.’

He nodded. ‘But here, you’re working in cooperation with others and against a common foe.’

Her eyes ran down the team names. ‘How anonymous is it?’ she asked.

‘How do you mean?’

‘I mean, does each player know who his team-mate is, or who’s on the opposing team?’

He stroked his beard. ‘At most, they’d have a nom de guerre.’

Siobhan thought of Philippa, with her secret e-mail name. ‘And people can have lots of names, right?’

‘Oh yes,’ he said. ‘You can amass dozens of names. People who’ve spoken to you a hundred times … they come back under a new name, and you don’t realise you already know them.’

‘So they can lie about themselves?’

‘If you want to call it that. This is the virtual world. Nothing’s “real” as such. So people are free to invent virtual lives for themselves.’

‘A case I’m working on, there’s a game involved.’

‘Which game?’

‘I don’t know. But it’s got levels called Hellbank and Stricture. Someone called Quizmaster seems to be in charge.’

He was stroking his beard again. Since sitting at the computer, he’d donned a pair of metal-rimmed glasses. The screen was reflected in the lenses, hiding his eyes. ‘I don’t know it,’ he said at last.

‘What does it sound like to you?’