"Magic is everywhere on the Disc," Albert explained as he, Lu-Tze, Ronnie, Susan and Vetinari pored over a map of the known continents and features. "In some places it's stronger than others, it can flow along the pathways we call ley lines. It can pool and ebb and form patterns in the same way Time forms patterns." The wizard and the Sweeper exchanged glances of agreement.
"But can there be such a thing as an anti-magic pattern? Is iron capable of creating such a thing?" Vetinari asked.
"We-ell," Albert considered, sniffling into a handkerchief. "Some types of magic are vulnerable to iron and some types are not. It all depends on the magic. Iron doesn't really flow, as such either. It tends to remain in nice big lumps right where it is, with minor amounts being dug up here and there, and getting scattered here and there as people use it. Iron doesn't form patterns."
"Until we dig up enough of it and distribute it across the world's surface in a way that isn't purely random," Vetinari stated, tracing a line on the map between Ankh-Morpork and Uberwald with his finger.
"The railroad tracks?" Susan murmured. "They're mostly steel and wood, not iron, aren't they? And there aren't enough of them to do much damage, are there?"
"Steel contains iron, and the rails are held together and held down to the ground by iron nails and iron spikes." Vetinari traced other lines, between Ankh-Morpork and Sto Lat and Quirm. "But there's more. Dwarves and humans have been mining more than just fat and treacle for hundreds of years. They mine the metals too, and pile up the mining wastes they consider too poor to process, the tailings, in huge amounts alongside the mines. Tailings don't contain much metal by miners' standards, but they do contain it, and there are many mines." And how many foundries? How many forges and armories? "Taken all together, might they not form a pattern? A very big pattern?"
"They could . . . ." Albert said. "But something like that would be noticeable, I should think."
"If someone wanted to notice it, you mean," Susan added. "I work as a schoolteacher and you would not believe the things parents and administrators refuse to notice, even when you try telling them face to face. I have to use a megaphone!" This was especially true of one or two budding young psychopaths and their families Susan cited as examples. With some parents, the megaphone was not enough. They simply wouldn't believe that their little Johnny or Darla throwing the class pet down an incinerator chute was any indication that there might be A Problem. If the parents were paying a high enough school fee, Madame Frout, the director of the School of Learning Through Play, might take some convincing too.
"Honestly," Susan shook her head, "sometimes I even have to use THE VOICE."
Vetinari required all of his self-possession not to start a little at the sound. The last two words that came out of Miss Susan's mouth were in the VOICE of DEATH, but with a female tone. It was a sound entirely appropriate when coming from a tall skeleton with glowing eye sockets, an obsidian robe and a scythe. But it was shocking beyond measure out of the mouth of a pert, modestly and modernly dressed young woman.
"How did you do that?" He asked, fascinated.
"LIKE THIS."
THE VOICE cost her no effort as far as Vetinari could see.
"Can you do other things that your grandfather can do?"
"Practically everything," she shrugged. "The usual. Invisibility. Walking through walls. Stepping outside of time. Remembering the Past and the Future, but only if I have to. THE VOICE. The Look. That sort of thing."
"And . . . ?"
"Killing people? Yes. But again, only if I have to. Only if it's their time." She shifted her posture and the three pale stripes reappeared on her face. "Now if we can stop talking about me, and get back to the discussion of patterns?"
Lu-Tze was the next to speak.
"It is as you say." He took a long drag on one of his hand-made cigarettes. "If seeing what is obvious were so easy, everyone might be a Monk of History. The flow of Time is all around us, but how many observe it? We are looking at a map of the world, but if every deposit of iron were marked on it, would we see a pattern or only disconnected dots?" He gave Ronnie Soak a sidelong glance as he said this and Ronnie gave him back a wink.
"A witch would see it," Albert sniffled and sneezed, rolling up the map. "A witch wouldn't need one of these. The most powerful of 'em have an intuitive feel for the land better than any wizard's, much as I hate to admit it."
"A witch did notice it," Vetinari sighed.
"Yes – Esmerelda Weatherwax, you said. That's right." Memory might have been Susan and Vetinari's strong point but it wasn't Albert's – at least not in all things. "So if the problem is one of pattern disruption or creation, it should be simple enough to fix. I can't go back to the Disc, and I don't think Mr. Vetinari can either, but that shouldn't be a problem for the rest of you." He nodded to Lu-Tze, Ronnie and Susan. "All you have to do is travel back there, find the disruptive or disrupted patterns, and convince people to alter them before they destroy the world."
"While fighting our way through maybe an army of Auditors who'll try to stop us." Susan didn't roll her eyes – she's come to despise that expression in others – but her voice clearly rolled its eyes. "I'm glad it won't actually be a problem."
"I can think of something else that won't be a problem either," Ronnie Soak said to them all, while suddenly peering out a window of the Library in Death's House. Something in the way he said it caused them all to pause and lean over to see what he was seeing. "Finding them."
On the starry, dark plain around the House, hundreds of little grey robes full of nothing had them surrounded.
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