“I don’t need to know,” said Johnny Boy.

“I’ll find it,” said Icarus. “If it can be found, I’ll find it.”

“I just bet you will. Would you like to know about the ghosts now?”

Icarus nodded.

“Well,” said Johnny Boy. “It happened like this. The professor was walking home one night from the station and you know that little passage you go down that leads to Abbadon Street?”

“I do,” said Icarus.

“He saw a ghost there. He didn’t know it was a ghost at first. He thought it was just a little old lady walking in front of him. It was night and there’s two street lamps about twenty yards apart. She passed into the light of one, then into the darkness beyond. And he walked on, but she didn’t appear in the light of the next street lamp, so he hurried forward, thinking she’d fallen over, or something. But she hadn’t, she’d vanished. And there’s high walls on either side, so he knew that she hadn’t climbed over.

“Then it occurred to the professor that there was something odd about the old woman. Apart from her just vanishing, of course. Something odd about her clothes. They were wrong, see? Old-fashioned. She wore a plaid shawl and a waxy Victorian bonnet. And then he realized that she was a Victorian old woman. She was a ghost.”

“So he somehow got her here?”

“Don’t be stupid, lad. The professor was a scientist. He had a scientific outlook. He reasoned that if he had seen a ghost there had to be a natural, rather than supernatural, explanation and one that science could suss out. So he applied his not inconsiderable store of wits to solving the mystery of ghosts.”

“And he solved it?”

“Shut your face, lad, and listen. People have all kinds of theories about ghosts. Lost souls. Shades doomed to wander this Earth in search of justice. Spirits being punished for crimes they had committed as men. Arbiters of doom. Et cetera and et cetera. But what the professor had seen seemed to him so mundane. It was just an old woman walking along. Probably as she had done in that passage hundreds of times. And that was the clue he needed to solve the mystery. Repetition, see. When people see ghosts, those ghosts are always seen doing a particular thing. Just walking along, mainly. So the professor reasoned that what people were actually seeing was a playback of the event.”

“Like a holographic image,” said Icarus.

“What the holy hellfire is that?”

“Something I read in a science fiction book.”

“Yeah, well it ain’t that. It’s a playback. The professor studied the location of the sighting. He tried to work it all out. Was it something about the location itself? Was it to do with atmospherics? He worked away like one possessed. He was always like that. And finally he worked it out. This world we live on is a bit like a great big capacitor. It stores up energy. You can call it psychic energy if you want, but that’s just a word. Everything that’s ever happened on this Earth leaves behind a residue. Everything. Like you leave behind a scent that a bloodhound can track. Your ghost is just a recording of an event, which can be played back if the conditions are absolutely right. Are you following this?”

“I think so,” said Icarus.

“So the professor set to work to invent a machine capable of creating the right conditions. An electrical machine, because all people really are, when you get right down to it, all everything is, when you get right down to it, is energy. Electrical energy, atoms vibrating, that sort of stuff. The professor figured that all you had to do was tune into the right wavelength, create the right frequency, beam it at a particular place, create the correct conditions for the playback of a particular event to become visible to the human eye.

“He tested it out in the house. Because he was also no fool, the professor, and he could see the enormous commercial potential for such an invention. Better than theme parks. Imagine if you could go to the Tower of London and actually see all those famous kings and queens of England, played back before your eyes, getting up to all sorts of business.”

“I can imagine,” said Icarus.

“He got all his apparatus set up and we gave it a test run and Winifred appeared. That was the little girl you saw first. The professor was delighted. I was scared witless, but he knew what he was doing. Kind of.”

“Kind of?”

“He tuned the machine back and forwards, up and down the scale, and they began to appear, one after another. You could tune it to Victorian times and see Winifred or Regency times and see Black Peter, the big huntsman, and so on and so forth. And even more creepy, you could tune it back to just minutes before and see yourself doing whatever you were doing then. I’d been having a root through one of his drawers and he wasn’t too keen about that.

“But the machine certainly worked and eventually we’d tuned it to every one of the people who had ever been in that front room. One hundred and six of them. Not that many really, considering how old the house is.

“We played them back one at a time and he had me research them from old paintings and photographs and we worked out pretty much who they all were. Apart from a few of them who didn’t seem to tie up anywhere. Wrong’uns they were, but we didn’t know it then.

“The professor was over the moon. He was all for patenting his machine and becoming very very wealthy. But things didn’t work out that way. Winifred kept appearing, even when the machine was switched off. And then, one by one, so did all the others, until you have the four o’clock furore that you saw today. And you can come back and see it all tomorrow if you want.”

“I don’t,” said Icarus.

“No, I’ll bet you don’t. This house will be a real stinker to sell, won’t it?”

“So you’re saying that once the ghosts had been made to appear by the use of the machine, they couldn’t be switched off.”

“Seems so. So you can just imagine what would have happened if the machine had been produced commercially. You wouldn’t be able to move for ghosts.”

“Does the machine still exist?”

Johnny Boy tapped at his nose. “Wouldn’t you like to know.”

“I would,” said Icarus. “Because if it did, we could play back the professor and see where he hid the formula, couldn’t we?”

“We could,” said Johnny Boy, stroking away at his little pointy chin. “If the machine did still exist. If the professor hadn’t smashed it to smithereens.”

“Well, it was a thought.”

“Yes it was, and a good one too.”

“Well,” said Icarus. “It’s an incredible story and an incredible invention, but it doesn’t help much with my search. Are you absolutely sure that you don’t know where the professor might have hidden the formula?”

Johnny Boy gave his head a shake. “I wish I did,” he said. “Because if I did, I’d manufacture the drug by the tanker load and dump it into the water supply. Then we’d see some fireworks.”

Icarus eyed the tiny man. “You know what the drug does, don’t you?”

Johnny Boy nodded.

Icarus sighed again. He got to his feet and stretched out his arms. “I will find it,” he said. “And when I find it, I’ll take it and I’ll know too.”

Johnny Boy grinned. “I hope I’m around to see that,” he said. “Perhaps you will change the world, eh?”

“Change the world.” Icarus glanced over at the map. “Why do you have that in here?” he asked.

“It’s pretty. It was a present. It arrived in the post yesterday, addressed to me. I don’t know who sent it.”

“What?”

“I don’t know. The envelope was typed. Free sample probably.”

“I think not.” Icarus stepped over to the map and gave it a bit of close-up perusal. “There are lines drawn on this map in biro,” he said. “Did you draw them?”

“I didn’t notice any lines.” Johnny Boy pushed in front of Icarus. “Where are these lines?”

“There and there. All over the place. They’re faint but you can see them.”