"Have you tried looking?" he said, and sped up.

She matched his pace. "I'm new here, I don't know anyone. I'm looking for my uncle."

"Family? Stay away from family. Family is bad news. My family can't stand me. You know why? Because I work hard. They're jealous. Everyone's jealous. Everyone's going home to their families but am I? I am not. I'm still working, that's what I'm doing. That's why they're jealous. It's not easy being me. It'd be easier being you, and I don't even know you. I know me, though, and I should get an award."

"I just need to find-"

"Need to find? Need to find? Why do you need to find? If you're looking for someone, search the Well."

"The what?"

"The Well. Are you stupid?"

"I'm not sure what that is."

He turned suddenly. "You don't know what the Well is? The World Well? You don't know what it is? What age are you?"

"Uh, seventeen."

"You're seventeen years old and you don't know what the World Well is? Where have you been? Where are you from? What's wrong with you? Are you stupid? Are you dim? Are you...?" He stopped suddenly, and for a moment he looked horrified. Valkyrie readied a power-slap, prepared to unleash it the moment he started to shout for help. Instead, he smiled. "Oh, I'm dreadfully sorry," he said, suddenly talking really slowly. "I didn't mean to be rude."

She frowned. "Uh... that's OK..."

He tilted his head towards her. "Different people learn at different rates. It's nothing to be embarrassed about."

"I'm sorry?"

"No no no, I'm the one who's sorry. I have a daughter myself, actually. You remind me of her. She's four."

Valkyrie glared. "Right."

"The World Well is a marvellous thing," said the man, talking even slower now. "Can you picture in your head a big bucket? Can you do that?"

"A bucket," Valkyrie said. "Yeah."

"And in this bucket, or this Well, is all the information in the world. It's all put in there. Every book ever written, every fact and figure. Do you understand?"

Valkyrie took a deep, calming breath. "Sure."

"Now, this is where it gets tricky. The bucket is, sort of, all around us. It's in the air, almost. It's in magic, and magic permeates everything. So if we want to check something, a fact or a figure, then we just dip our little handies in the bucket, and pull out what we want to know."

She looked at him. Didn't say anything.

"So," the man said, "you're looking for your uncle, isn't that right? What's his name? Do you know his name? Maybe your mammy or your daddy wrote it down on a piece of paper for you?"

"Walden," Valkyrie said, trying to smile. "Walden D'Essai."

"Walden D'Essai," he repeated. "OK. Just give me a moment and I'll check for you." He smiled at her, his eyes going glassy. If it turned out that Walden wasn't a resident of the City, Valkyrie prepared herself to look particularly dim-witted. If it turned out he was dead, she prepared herself to look distraught. "Ah, here he is. Oh, your uncle is a very important man. He's in charge of sewage, did you know that? The City would be a very stinky place if it wasn't for great people like your Uncle Walden."

"Where does he live?"

The man took a moment, then smiled again. "Found it. He lives at number eighteen Mount Temple Place. That's all the way on the other side of the City. I don't think you'd be able to walk there." He chuckled. "Do you want to get a taxi?"

Valkyrie nodded, started walking away. "That sounds like a good idea."

"Do you have any money?"

She stopped. Dammit.

She turned and he gave her a few coins. "There. That should get you to your Uncle Walden and you'll have enough left over for an ice cream. Do you like ice cream?"

Valkyrie muttered under her breath.

He beamed, and waved down a passing carriage. The driver diverted from the airstream, and set down beside them. "Eighteen Mount Temple Place," the man instructed as she got in. "You say hi to your uncle for me, won't you? And thank him for doing such a wonderful job with the sewage!"

"I will," Valkyrie murmured, and sat back as the carriage lifted off the ground and rejoined the stream. It flew round the corner, where she leaned forward and tapped the driver. "Pull over for a second, would you?"

He did as she told him, and a moment later, the door opened and Skulduggery and Serpine climbed in. When they were moving again, she looked at Serpine. "Why couldn't you use the Well to find out where he is?"

"I'd be detected immediately," he said. "Things like the World Well, everyone thinks it's about sharing information, but it's just another tool for Mevolent to keep track of you."

"The Well?" asked Skulduggery.

"Magical Internet," said Valkyrie.

"Ah."

They got to 18 Mount Temple Place. It was a two-storey house on a rising hill, its architecture identical to the buildings around it. They did a quick sweep of the area.

"D'Essai's security system is a good deal more elaborate than any of his neighbours'," Skulduggery said. "We'd need a few hours to break in, but if he's on his way home with everyone else, we probably only have minutes."

"It will deactivate when he enters," said Serpine. "If one of us distracts him immediately upon opening this door, the other two can use the opportunity to sneak in through the back. Seeing as how I have a recognisable face, it can't be me."

"I'll do it," Valkyrie said.

They went round the back and Valkyrie hung around on the street, doing her best to look inconspicuous. No one gave her a second look. She saw Walden D'Essai coming up the hill, and gave the signal to get ready by running a hand through her hair. Walden passed her, opened his front door and Valkyrie said, "Mr D'Essai?"

He turned. "Yes, hello. Can I help you?"

"I hope so," she said, and smiled. "My name is Valkyrie Cain. Could I speak with you for a moment?"

"Regarding?"

"Your work."

He smiled. "And why would a young lady like yourself be interested in Sewage Maintenance?"

"Honestly? The glamour."

The smile turned to a laugh. "Do you mind telling me what you really want to talk about?"

"It's of... a personal nature."

He looked at her, and took a moment. "I'm sorry, I don't think I can help you."

"You're the only one who can."

"Then you have me mixed up with someone else. I'm sorry."

He stepped inside and closed the door. Valkyrie stayed where she was. A few seconds later, the door opened, and Serpine beckoned her inside.

It was a tastefully decorated interior, and would probably have been neat and tidy were it not filled with books and notepads. Walden sat stiffly in what looked like his favourite armchair. He looked around, scared. "Take what you want. It's not worth much but I won't call the authorities, you have my word."

"We're not here to rob you," Skulduggery said, and the face he was wearing smiled gently.

Valkyrie picked up a few of the books, flicked through them. "Heavy reading for a Sewage Maintenance Engineer," she said. "Realms of Magic. The Existence Equation. Philosophy and Sorcery. Between Gods and Man: The Next Stages of Human Evolution."

"It looks like you have an interesting hobby," said Skulduggery. "So how does someone who clearly wants to explore magic, and where magic comes from, find himself working in the sewers?"

"It's nothing," Walden said. "Just a few books. It means nothing. Please. If you don't want to rob me, why are you here? What do you want with me?"

"I've been asking them the same question," Serpine said.

"Walden," said Skulduggery, sitting on the couch opposite him, "we're not from here."

"What do you mean?"

"I mean, we're not from this world."

"I don't... I don't understand..."

Serpine shrugged. "It's true. I know it sounds ridiculous, but it's true. They're not from here."

Walden blinked at Skulduggery. "Then... then you're... you're aliens?"

Before Skulduggery could reply, words spilled from Walden's mouth. "Oh, I knew it! I knew it! I knew we couldn't be alone in the universe! When I was a kid, they laughed at me but I knew there was something more to life, more than this world and this level of magic and the day-to-day grind of living, and here you are, sitting across from me, a real-live alien being! Do you have a flying saucer? Could you take me up in it?"

Skulduggery didn't answer right away. "Uh..." he said.

Valkyrie stepped forward. "We're not aliens. We're from a parallel dimension."

Walden's face fell. "Oh."

"But look," Skulduggery said. He tapped his collarbones and his face flowed away. "I'm a skeleton."

Walden nodded, unimpressed. "Right. So why are you here, then? I have a lot of work to do."

"We need your help."

"Why?"

"We can't tell you."

"Well, that's just wonderful."

"Will you help us?"

"If I help you, will you leave?"

"Yes."

"Then I would really like to help you. But I won't if it's going to get me into trouble."

"There'll be no trouble."

"But you answer me a question first. Who is that?"

Serpine arched an eyebrow. "Me?"

Walden nodded. "I know you from somewhere. I know your face. But I'm not good with faces. Who are you?"

"They've called me a great many things over the years, but my name is Nefarian Serpine."

Walden's face went slack. "The traitor."

"Yep, that's one of the things they called me."

Walden stood up so quickly he knocked his chair over. His voice rose in volume. "I can't talk to you. I can't talk to him. I can't associate with him. Do you know what would happen to me if the Sense-Wardens found this moment in my mind? I'd be arrested. I'd be tortured!"

"That's not going to happen," Skulduggery said calmly.

"You don't know that!" Walden said, panicking. "I'm doomed. I'm dead. They're going to arrest me!"

"Walden," Skulduggery said, "sit down. Take a deep breath."

"I can't! I can't breathe!"

"There's no need to panic. The sooner you help us, the sooner we'll be out of here."

"Go!" he shouted. "Leave! Leave before I call the City Mages!"

"First we need to talk."

Walden covered his face with his hands. "Please," he said. "Please leave me alone."

"In a minute. Walden, we have an emergency back in our dimension, and you're the only one who can help us."

"Why me?"