Zac sat on the back seat of the car, looking out through the tinted windows. The two angels were sitting across from him. Michael looked a little more relaxed. His angry scowl had become merely an irritated sneer. Gabriel's smile, on the other hand, looked to be just hitting its stride.

There was a darkened screen between the back of the car and the front, meaning Zac couldn't see the driver. Then again, with everything that had happened in the past hour, he couldn't even be sure there was one.

Zac tried to take in the sights of the city around them. Every building was like a palace, each having more marble columns than the one before. The striped lawns in every garden were a vibrant, almost neon, green. The flowers too were more vivid than any Zac had seen. It was as if they had been coloured using crayons from a child's art set, where reds were red and blues were blue, and pastel shades didn't get a look in.

"The streets," said Zac, as they passed another palace. "They're proper streets. They're not wispy like at the gate."

"Ah, yes, the cloud effects. That's just for the tourists," Gabriel said. "Costs us a fortune in dry ice, but then where would we be if we didn't keep up appearances?" He gave Zac's black clothing a very deliberate glance. "Wouldn't you agree?"

There was a soft knock on the other side of the dividing screen, and the vehicle began to slow. Michael peered out through one of the side windows for a moment, before announcing, "We're here."

The car whispered to a stop and the doors opened automatically. "We're where?" Zac asked.

"See for yourself," suggested Gabriel.

Zac stepped out of the car and found himself outside an enormous, sprawling citadel. He'd thought the other buildings they'd passed had been palaces, but compared to this place they were little more than shacks.

A thousand white pillars stood by the smooth walls, each one carved to resemble a giant kneeling angel with wings fully unfurled. They all had their hands raised, supporting the overhang of a domed roof that was made up of intertwining bands of gold and platinum.

Light seemed to emanate from within the dome, bright enough to make a dull ache throb at the back of Zac's eyeballs.

There was sound too. It wasn't quite music; it was something more, or something less. Like the music that existed before music. A prototype version of music that bypassed the ears and launched a full-scale assault on the emotional centre of the brain instead.

Zac didn't notice Gabriel step out of the car behind him. He didn't even pull away when the angel's hand patted him on the shoulder.

"Nice, isn't it?"

"Not really my cup of tea," Zac said, pulling himself together. "What is it?"

"This? This is the house that God built," said Gabriel. He stepped past the boy and gestured towards the building's ornate front door. "Shall we step inside?"

Zac sat at one end of a long narrow table in a long narrow room. The table was made of dark wood, polished to a mirror-like shine. There were twelve leather office-style chairs positioned round it, evenly spaced. Filing cabinets and bookshelves lined one of the room's shorter walls. Over in the corner stood a water cooler. Every few minutes, it gave a loud glug and bubbles rose lazily inside the bottle.

Compared to the outside of the building, this room was relatively dull. There were windows, but Gabriel had closed the blinds as soon as they'd entered. A pot plant stood by the largest window, five completely different types of flower blooming from its stalks. Zac didn't recognise any of them.

At the far end of the table, directly opposite Zac, Gabriel lowered himself into one of the leather chairs. He leaned forward, his elbows on the tabletop, his fingers steepled in front of his mouth, his blue eyes sparkling.

Michael had been right behind Zac as they'd entered the room, but he hadn't followed the others in. There were only the two of them there now a" the boy and the angel.

"Well?" said Zac. "You wanted to talk. I'm listening."

Gabriel waited a few moments before speaking. "We've misplaced something," he said, choosing his words carefully. "We would like you to help get it back."

"Why me?"

"Because we believe your unique talents and your... past exploits make you the perfect choice for the job. We need someone fast. Someone who can think on their feet and who is not afraid to fight dirty, should the need arise."

"Then why not send the Monk? He beat me."

"Alas, the Monk is well known to those who have taken the item. He would not, I fear, last two minutes."

"Why?" Zac asked. "Where is it?"

"Hell," Gabriel said. His chair creaked as he leaned back, not taking his eyes off Zac. He was watching for some kind of reaction, Zac knew. A look of shock, or fear, or something. But Zac wasn't about to give him the satisfaction.

"Right. And what was taken?"

One of Gabriel's eyebrows rose a few millimetres in surprise. "Did you hear what I said?"

"It's in Hell, yeah. I heard. What was taken?"

"A book."

"What book?"

"It is a book with many names," the angel said. "Down there they call it the Book of Doom. Up here we prefer the Book of Everything."

"Sounds like a children's encyclopedia," Zac said.

"Oh, I assure you, it isn't. The Book of Everything tells us... well, it tells us everything. Every shift of every grain of sand. Every movement of every cloud. Every thought inside the minds of every living creature, from the very beginning of time until the very end." Gabriel paused a moment, to let his words sink in. "It is omniscience. In paperback form."

"I can see why you'd want that back."

"Indeed. With the book in the hands of our enemies, there is nothing they could not do. No one they could not corrupt. Nowhere they could not conquer. Knowledge is power, and the Book of Everything contains all the knowledge in existence. In the wrong hands, it is the deadliest weapon in all of creation."

Zac whistled through his teeth. "So, that's why they call it the Book of Doom."

"Correct," said Gabriel. "In their hands it could indeed doom us all."

"If the book tells them everything, won't they know I'm coming?"

"Almost certainly," Gabriel admitted. "I never said it was going to be easy. There's every chance you will not make it back."

"You're not really selling the idea," Zac said.

"I am nothing if not honest," Gabriel said, although Zac seriously doubted that. "And you are dead, remember? Either way you are going to Hell. At least our way there's a chance, however slim, that you will be able to return."

Zac found himself thinking about his grandfather, all alone in that big house with only a hyperactive goldfish and the voices in his head for company.

"Right. So, what does it look like, this book?" he asked, forcing himself back to the matter at hand.

"We don't know."

Zac frowned. "Well, when was it taken?"

"We don't know that, either," Gabriel said, giving a shrug of his slender shoulders. "It's all rather complicated, I'm afraid."

"Apparently I've got plenty of time on my hands. Uncomplicate it."

Gabriel gave a single nod. "Of course." He stood up and rolled his chair into position beneath the table, then rested his hands on the chair's leather back.

"The Book of Everything can take many forms," he began. "I, for example, may see it as a small, compact paperback. You may see it as a leather-bound tome. Some may look upon the book and see a carving on a stone tablet, or scribbles in a spiral-bound notebook, or a" Lord help us a" one of those awful electronic reading devices. Or even something else entirely. The branch of a tree, perhaps. Or a small flan. Nobody knows how they'll see it until they see it."

"Then how am I supposed to find it?" Zac asked.

"Because you will know it, when you see it. We shall grant you that ability. There will be no glimmer of doubt in your mind."

"Fair enough. You said you didn't know when it was stolen," Zac prompted.

"Yes, I did say that, didn't I," said Gabriel. He walked over to the pot plant and cupped one of its leaves in his hands. Another flower burst into bloom further along the stalk. The angel bent, sniffed the flower's yellow and pink petals, then nodded his approval.

"OK, well, let's narrow it down," said Zac, when he realised no more information was forthcoming. "When did you last see it?"

"Yesterday."

Zac felt himself frown again. It was becoming a habit. "So... obviously someone took it in the last twenty-four hours."

"Not necessarily," Gabriel explained, turning back to face him. "The Book of Everything exists outside of time. In many ways, I suppose, you could say that it is time. I saw it yesterday, but that doesn't mean it wasn't taken a thousand years ago. Or tomorrow."

"I don't understand," admitted Zac.

"No. It's not an easy one to get your head around, is it? We tried explaining it to Albert Einstein once, shortly after he got here. He's been having a lie-down in a darkened room ever since. Whimpering into a pillow, by all accounts." Gabriel flashed his politician-smile again. "So let's not go into too much detail. Suffice to say the book has been taken at some point and that right now it is in the possession of Hell and all its minions."

The door opened and Michael strode in. Zac saw a subtle look pass between the angels, and the briefest of nods from the one in the armour.

Gabriel took his seat again, while Michael remained standing behind him. Both angels looked expectantly at Zac.

"Our offer is this," said Gabriel, clasping his hands together. "You find the book and bring it to us, and we wipe the slate clean. A fresh start. You are returned to life, and all your sins are forgiven."

"And if I say no?"

"Then you will still go to Hell, but as a prisoner of Satan, not as an agent of God. There you will be roasted, flayed, impaled and so on and so forth, for the remainder of time."

Zac didn't flinch. He held Gabriel's gaze. The angel shifted in his seat slightly, then leaned back and placed his hands behind his head.

"And then, of course, there's your grandfather to think about."

The tiny hairs on the back of Zac's neck stood on end. He almost reacted to that, but he bit down hard on the inside of his bottom lip to stop himself.

"He's how old now? Ninety-six? Ninety-seven?" Gabriel asked, not expecting an answer. "Old for a human. All alone down there. Defenceless. How is his health these days? The mind can start going at that age, can't it? Wouldn't it be a shame if you could never go back to him? Never even got the chance to say goodbye?"

Zac's voice was like the rasp of a saw. "OK," he said. "You win. I'll do it."

"Excellent. Excellent," said Gabriel. He spun his chair in a full circle, then stood up suddenly. "Michael will accompany you on the quest."

"No, thanks," Zac said.

Gabriel raised both impeccable eyebrows. "I beg your pardon?"

"I don't want him with me."

"Why ever not?"

"I don't like him. I'll go alone."

"I'm afraid that's quite impossible. Without him, you would not be able to cross over the barriers between realms." Gabriel gave a dismissive wave. "Michael will get you out of Heaven, and Michael can bring you into Hell. You could not do these things on your own."

"Then I'll take someone else," Zac said. He met Michael's furious glare and shot it back at him. "Preferably someone who hasn't held a sword to my throat. In fact, preferably not an angel at all."

Gabriel laughed a hollow laugh. "This is Heaven. I'm afraid angels are all we have. But I don't understand a" why don't you want an angel to accompany you?"

"Because an angel in Hell is going to stand out, I'm guessing. I want to get in and out without making a scene," Zac said. "Also, I'm still an atheist, so technically I don't even believe in angels. You two included."

"Well, I'm afraid there's nobody else," Gabriel said. He tapped a manicured fingernail against his flawless teeth. It made a sound like footsteps on marble. "Unless..."

"Unless what?"

"There is one who may be able to help, although he has nowhere near the strength or experience of Michael."

"I don't need strength or experience, I just need a guide," Zac shrugged. "Is he an angel?"

Gabriel shook his head. "No."

"What's his name?"

"His name? It's... ah... yes. His name is Angelo."

"Angelo?" said Zac flatly. "And he's not an angel?"

"No. Yes. Well he's half angel. But he's the closest thing to a human that we have."

Zac jumped up and pulled the drawstring of the closest blinds. They lifted, letting a flood of sunlight into the room. He gestured at the busy city-centre plaza beyond the glass, and the hundreds of people who milled about there, all happily going about their business.

"Humans," Zac said. "Dead ones, maybe, but humans. What about one of them?"

"Send a guest?" Gabriel gasped, his eyes widening. "We couldn't possibly do that. Think of the paperwork. No," he said, shaking his head. "It is Angelo, or it is Michael. The choice, Zac Corgan, is yours."

"Angelo, then," said Zac. It wasn't a difficult decision. He'd met Michael less than an hour ago, but already he wanted to stay as far away from him as possible.

"Very good," said Gabriel. "Michael, would you be so kind as to fetch young Angelo for me?"

Michael nodded, shot a final glare at Zac, then pulled open the door. A look of exaggerated surprise crossed his face. "Oh, now would you look at that," he said. "What are the chances?"

He let the door open all the way. Gabriel looked past the other archangel and then he too reacted with shock. "Angelo? Just walking past at that very moment! What a stroke of good fortune."

Michael stepped aside. Zac saw the figure framed in the doorway.

"Oh, come on," he sighed as Angelo shuffled into the room. "You have got to be kidding me."