Guards! Guards!

and the crowded square. Because it didn’t look real, that’s why. If it isn’t real, it doesn’t need to do anything we expect. How can it walk out of an alley it didn’t go into?
    Once you’ve ruled out the impossible then whatever is left, however improbable, must be the truth. The problem lay in working out what was impossible, of course. That was the trick, all right.
    There was also the curious incident of the orangutan in the night-time…

    By day the Library buzzed with activity. Vimes moved through it diffidently. Strictly speaking, he could go anywhere in the city, but the University had always held that it fell under thaumaturgical law and he felt it wouldn’t be wise to make the kind of enemies where you were lucky to end up the same temperature, let alone the same shape.
    He found the Librarian hunched over his desk. The ape gave him an expectant look.
    “Haven’t found it yet. Sorry,” said Vimes. “Enquiries are continuing. But there is a little help you can give me.”
    “Oook?”
    “Well, this is a magical library, right? I mean, these books are sort of intelligent, isn’t that so? So I’ve been thinking: I bet if I got in here at night, they’d soon kick up a fuss. Because they don’t know me. But if they did know me, they’d probably not mind. So whoever took the book would have to be a wizard, wouldn’t they? Or someone who works for the University, at any rate.”
    The Librarian glanced from side to side, then grasped Vimes’s hand and led him into the seclusion of a couple of bookshelves. Only then did he nod his head.
    “Someone they know?”
    A shrug, and then another nod.
    “That’s why you told us, is it?”
    “Oook.”
    “And not the University Council?”
    “Oook.”
    “Any idea who it is?”
    The Librarian shrugged, a decidedly expressive gesture for a body which was basically a sack between a pair of shoulderblades.
    “Well, it’s something. Let me know if any other strange things happen, won’t you?” Vimes looked up at the banks of shelves. “Stranger than usual, I mean.”
    “Oook.”
    “Thank you. It’s a pleasure to meet a citizen who regards it as their duty to assist the Watch.”
    The Librarian gave him a banana.
    Vimes felt curiously elated as he stepped out into the city’s throbbing streets again. He was definitely detecting things. They were little bits of things, like a jigsaw. No one of them made any real sense, but they all hinted at a bigger picture. All he needed to do was find a corner, or a bit of an edge…
    He was pretty certain it wasn’t a wizard, whatever the Librarian might think. Not a proper, paid-up wizard. This sort of thing wasn’t their style.
    And there was, of course, this business about the lair. The most sensible course would be to wait and see if the dragon turned up tonight, and try and see where . That meant a high place. Was there some way of detecting dragons themselves? He’d had a look at Cut-me-own-Throat Dibbler’s dragon detectors, which consisted solely of a piece of wood on a metal stick. When the stick was burned through, you’d found your dragon. Like a lot of Cut-me-own-Throat’s devices, it was completely efficient in its own special way while at the same time being totally useless.
    There had to be a better way of finding the thing than waiting until your fingers were burned off.

    The setting sun spread out on the horizon like a lightly-poached egg.
    The rooftops of Ankh-Morpork sprouted a fine array of gargoyles even in normal times, but now they were alive with as ghastly an array of faces as ever were seen outside a woodcut about the evils of gin-drinking among the non-woodcut-buying classes. Many of the faces were attached to bodies holding a fearsome array of homely weapons that had been handed down from generation to generation for centuries, often with some force.
    From his perch on the roof of the Watch House Vimes could see the wizards lining the rooftops of the University, and the gangs of opportunist hoard-researchers waiting in the streets, shovels at the ready. If the dragon really did have a bed somewhere in the city, then it would be sleeping on the floor tomorrow.
    From somewhere below came the cry of Cut-me-own-Throat Dibbler, or one of his colleagues, selling hot sausages. Vimes felt a sudden surge of civic pride. There had to be something right about a citizenry which, when faced with catastrophe, thought about selling sausages to the participants.
    The city waited. A few