The leap wasn’t intentional. Her hindbrain arranged it all by itself. The front brain, the bit that knew that sergeants should not attempt to disembowel lance constables without provocation, tried to stop the leap in mid-air, but by then simple ballistics were in charge. All she managed was a mid-air twist, and struck the soft wall with her shoulder.

Wings fluttered a little way off, and there was a drawn-out organic sound, a sound that conveyed the idea that a slaughterhouse man was having some difficulty with a tricky bit of gristle.

“You know, Sergeant,” said the voice of Sally, as if nothing had happened, “you werewolves have it easy. You stay one thing and you don’t have any problems with body mass. Do you know how many bats I have to become for my body weight? More than a hundred and fifty, that’s how many. And there’s always one, isn’t there, that gets lost or flies the wrong way? You can’t think straight unless you get your bats together. And I’m not even going to touch on the subject of reassimilation. It’s like the biggest sneeze you can think of. Backwards.”

There was no point in modesty, not down here in the dark. Angua forced herself to change back, every brain cell piling in to outvote tooth and claw. Anger helped.

“Why the hell are you here?” she said, when she had a mouth that worked.

“I’m off duty,” said Sally, stepping forward. “I thought I’d see what I could find.” She was totally naked.

“You couldn’t have been so lucky!” Angua growled.

“Oh, I don’t have your nose, Sergeant,” said Sally, with a sweet smile. “But I was using a hundred and fifty pretty good flying ones, and they can cover a lot of ground.”

“I thought vampires could rematerialize their clothes,” said Angua accusingly. “Otto Chriek can!”

“Females can’t. We don’t know why. It’s probably part of the whole underwired-nightdress business. That’s where you score again, of course. When you’re in one hundred and fifty bat bodies, it’s quite hard to remember to keep two of them carrying a pair of pants.” Sally looked up at the ceiling, and sighed. “Look, I can see where this is going. It’s going to be about Captain Carrot, isn’t it…”

“I saw the way you were smiling at him!”

“I’m sorry! We can be very personable! It’s a vampire thing!”

“You were so keen to impress him, eh!”

“And you aren’t? He’s the kind of man anyone would want to impress!”

They watched each other warily.

“He is mine, you know,” said Angua, feeling the nascent claws strain under her fingernails.

“You’re his, you mean!” said Sally. “You know it works like that. You trail after him!”

“I’m sorry! It’s a werewolf thing!” Angua yelled.

“Hold it!” Sally thrust both hands in front of her in a gesture of peace. “There’s something we’d better sort before this goes any further!”

“Yeah?”

“Yes. We’re both wearing nothing, we’re standing in what, you may have noticed, is increasingly turning into mud, and we’re squaring up to fight. Okay. But there’s something missing, yes?”

“And that is…?”

“A paying audience? We could make a fortune.” Sally winked. “Or we could do the job we came here to do.”

Angua forced her body to relax. She should have been saying that. She was the sergeant, wasn’t she?

“All right, all right,” she said. “We’re both here, okay? Let’s leave it at that. Were you saying that these dwarfs were killed by some…thing from the well?”

“Possibly. But if they were, it used an axe,” said Sally. “Take a look. Scrape some of the mud away. It’s been oozing over them since I arrived. That’s probably why you missed it,” she added generously.

Angua hauled one dwarf out of the shining slime.

“I see,” she said, letting the body fall back. “This one hasn’t been dead two days. Not much effort made to hide them, I see.”

“Why bother? They’ve stopped pumping out these tunnels, the props look pretty temporary, the mud’s coming back. Besides, who’d be stupid enough to come down here?”

A piece of wall slithered down, with a sticky, organic, cow-pat sort of noise. Little plops and trickles filled the tunnel. Ankh-Morpork’s underworld was stealthily reclaiming its own.

Angua closed her eyes and concentrated. The slime reek, the vampire’s smell, and the water that was now ankle-deep all jostled for attention, but this was competition time. She couldn’t let a vampire take the lead. That would be so…traditional.

“There were other dwarfs,” she murmured. “Two—no, three…er, four more. I’m getting…the black oil. Distant blood. Down the tunnel.” She stood up so sharply that she nearly hit her head on the tunnel roof. “C’mon!”

“It’s getting a bit unsafe—”

“We could solve this! Come on! You can’t be afraid of dying!”

Angua plunged away.

“And you think spending a few thousand years buried in sludge is likely to be fun?” shouted Sally, but she was talking only to dripping mud and fetid air. She hesitated a moment, groaned, and followed Angua.

Further along the main tunnel there were more passages branching off. On either side, rivers of mud, like cool lava, were already flowing out of them. Sally splashed past something that looked like a huge copper trumpet, turning gently on the current.

The tunnel was better built here than the ones nearer the well. And there, at the end of it, was a pale light, and Angua, crouched by one of the big, round dwarf doors. Sally paid her no attention. She barely glanced at the dwarf slumped with his back against the bottom of the door.

Instead, she stared at the symbol scrawled large on the metal. It was big and crude, and might be a round, staring eye with a tail, and it gleamed with the greeny-white glow of vurms.

“He wrote it in his blood,” said Angua, without looking up. “They left him for dead, but he was only dying, you see. He managed to make it to here, but the killers had shut the door. He scratched at it, smell here, and he’s worn away his fingernails. Then he made that sign in his own warm blood and sat here, holding the wound shut, watching the vurms turn up. I’d say he’s been dead for eighteen hours or so. Hmm?”

“I think we should get out of here right now,” said Sally, backing away. “Do you know what that sign means?”

“I know it’s mine sign, that’s all. Do you know what it means?”

“No, but I know it’s one of the really bad ones. It’s not good seeing it here. What are you doing with that body?” Sally backed away further.

“Trying to find out who he was,” said Angua, searching the dwarf’s clothing. “It’s the sort of thing we do in the Watch. We don’t stand around getting worried about drawings on the wall. What’s the problem?”

“Right now?” said the vampire. “He’s…oozing a bit…”

“If I can stand it, so can you. You see a lot of blood in this job. Don’t attempt to drink it, that’s my advice,” said Angua, still rummaging. “Ah…he’s got a rune necklace. And…” she pulled a hand out of the dead dwarf’s jerkin, “can’t make this out very well, but I can smell ink, so it may be a letter. Okay. Let’s get out of here.” She stood up. “Did you hear me?”

“The sign was written by someone dying,” said Sally, still keeping her distance.

“Well?”

“It’s probably a curse.”

“So? We didn’t kill him,” said Angua, getting to her feet with some difficulty.

They looked down at the liquid mud now rising to their knees.

“Do you think it cares?” said Sally matter-of-factly.

“No, but I think there may be another way out in that last tunnel we passed,” said Angua, looking back along the tunnel.

She pointed. Scuttling along with blind determination, a line of vurms marched along the dripping roof almost as fast as the mud flowed down below. They were heading into the side tunnel in a glowing stream.

Sally shrugged. “It’s worth a try, yes?”

They left, and the sound of their splashing soon died away.

Slowly the mud rose, rustling in the gloom. The trail of vurms gradually disappeared overhead. The vurms that made the sign remained though, because such a feast as this was worth dying for.

Their glow winked out, one insect at a time.

The darkness beneath the world caressed the sign, which flamed red and died.

Darkness remained.