It was a perfectly normal day in Ankh-Morpork.
This being Ankh-Morpork, it was probably eight and a half bad days in any other town.
C.W. St. J. Nobbs, also known as Nobby, strolled down the Street of Cunning Artificers, and it immediately became about two bad days worse.
He'd been chosen for this particular patrol for one of his more stellar qualities--namely, his virtual indestructibility. Other stellar qualities hadn't yet been found.
People like Detritus were chosen to patrol the area around the Alchemist's Guild because the place blew up very reliably--if you weren't made of rock, you'd probably find yourself in a very intimate relationship with it.
People like Nobby patrolled the Street of Cunning Artificers because it wasn't often engulfed in a wave of fiery chemical death. Not usually. Not unless an artificer had been a bit too cunning. The alchemists didn't have time to commit crimes because whenever they weren't rebuilding their guildhouse, they were finding new and ingenious ways to bring it crashing down again. The artificers, on the other hand, were generally prosperous, upstanding citizens with free time and amusing hobbies. Commander Vimes reckoned that this was a recipe for some type of crime, and had acted accordingly. He had only two officers who could survive massive explosions and were subtle enough to poke around for evidence of crimes without attracting suspicion. Dorfl and Angua were far too useful where they were, and so Nobby had been given the job.
Not that he minded. Gregor Swiggs had that really interesting shop halfway down the street--Nobby hadn't known that you could make those kinds of things with just rubber and a bit of leather and metal--and anyway it was official. He was allowed out in broad daylight--in public. Had to be official; possibly it was an official mistake, but the assignment smacked of officialness anyway, and just a light jab of officialness was enough to make him puff out his chest as he walked down the street. It made him look as though someone invisible was leading him by a string tied to his ribcage.
Events often hinge on little things we see from the corners of our eyes. Policemen learn to be very good at seeing out of the corners of their eyes; no self-respecting unlicensed criminal will stand in a policeman's direct line of vision. Though now, with the perversity of adaptation, the more intelligent criminals would walk cheerfully down the street, wave at the watchman patrolling, and be completely ignored by the dumb sod who was concentrating too hard on the periphery.
What Nobby saw from the corner of what seemed to be his eye would have made even a blind goat do a double take.
He sidled back and looked at the sign again. He read the large words, then the smaller words beneath them, and finally the smallest words at the bottom. Even in his quasi-villainous mind, this stood out as particularly dastardly.
"This can't be legal," he muttered around the dog-end of a cigarette, and he slouched toward the watch house in Psuedopolis Yard at a much livelier pace.
~
It's a well-known fact that any office in which the owner acts as his own secretary is always littered with enough paper to make an environmentalist weep. It's a lesser-known but still formidable fact that somewhere, under the curry-stains, mouldering memos, and missing pens, there's room for sentience to develop.
This may have been why, when Sergeant Colon knocked cautiously on the door to Commander Vimes' office, he appeared with a butterfly net in one hand and a knife in the other. Judging by the scorch-marks on his clothing, though, he was dealing with one of his wife's escaped pets. The oven mitts (or the charred remains thereof) on his desk might also have been a clue. On general principle, Colon saluted.
"Sah! Nobody's found something that's probably illegal in the Street of Cunning Artificers, sah!"
"What is it?" Vimes replied, swooping around and bringing the net down on a small green blur. A belch of flame turned the butterfly net into a hoop with a handle. "Damn!"
"Christopher Combustus has opened a shop that pervys exploding devices, sah!"
The sergeant received a look that said that the commander had been hunting down a small exploding device for the past hour with little to no success. It said, in very plain language, that Mr. Combustus could bloody well pervy all the exploding devices he liked.
"And they're supposed to explode, sah!"
There was a pause.
The swamp dragon burped a plume of smoke and curled up on a nest of dispatches. Vimes upended his wastebasket on the creature.
"Supposed to explode?"
"Yessir! That's what Nobby said!"
"Do they?"
~
Crispy Glass wasn't a large man or a strong man. He didn't have the requisite overlarge head that defined the intellectual elite. He was short, and thin, and had very quick eyes. If you saw him on the street, you'd report him to the Watch--someone like that seemed able to steal from you just by looking at you.
Crispy Glass had a very straightforward mind, particularly when it came to devices. If they didn't work, you dismantled them. If they still didn't work, you hadn't dismantled them properly. If something was an inconvenience, he steamrollered over it. It was a mind like a stick of dynamite. Against a mind like this, even the absentminded diabolical genius of Leonard of Quirm seemed tame.
This was the man that most knew as Christopher Combustus, Purveyor of Explosive Devices at a Fair and Reasonable Price to All.
His wife had chosen the name. Thelma was not straightforward. She was not methodical or brilliant. But she knew that Crispy Glass wouldn't be able to purvey half as many Explosive Devices as Christopher Combustus. In this respect, she had a mind as singular as her husband's.
Everyone has a kind of genius. Some may become experts on the habits of earthworms. Some develop a passion for floral arrangements. Some develop nuclear theories as a hobby. Everyone has his or her own kind of brilliance. Christopher and Thelma Combustus had found their niches and wedged into them.
Christopher was currently wedged into a different kind of niche. He sat in the corner of his shop, surrounded by saltpeter and trinitrotoluene and the ingredients for a fireball of massive proportions. He was filling a tube with shards of sharp metal.
"Hello. Carrot Ironfoundersson, am I right?" He hadn't looked up.
"Christopher Combustus, Purveyor of Explosive Devices at a Fair and Reasonable Price to All?" Carrot glanced around the shop with the awe of Chihuahua surrounded by sleeping Dobermans. "Do they work?"
"If they didn't work, I wouldn't sell them." He still didn't look up.
"Thank you. That's all I needed to know."
"Are you certain that's all you need to know?" Christopher Combustus absently ran a hand over the wall beside him for a moment, finally hitting the peg on which he kept his goggles. "I could offer the Watch a few exploding devices, if you like. They really work quite well. And it might be easier to deal with the really difficult criminals if you had, ah, irresistible backup."
Carrot's expression was the puzzled half-smile, half-frown of someone who hadn't worked out whether he was being told a joke or not. "It's hard to apprehend a criminal when he's a crispy stain on the walls."
Christopher tightened the strap of his goggles and pulled them over his head. He carefully poured a small decanter's chemicals into a tray of dark powder. "But not harder, I would think, to make sure that he never commits a crime again."