They climbed upwards again. The steps and walls and ceiling all seemed to be carved from the same material. It felt like wood, but it wasn't polished, and there were no planks or joints. It seemed to be all in one piece, slightly rough to touch, and slightly warmer than the air they were breathing.

“Do you think that was the same snake?” puffed Adam. “The one with its tail in its mouth, like on the card?”

“I don't know. I suppose so. There can't be more than one, can there?”

“Then if that was its own tail,” said Adam, “how big was the snake? I mean, how big was the loop it made? I don't think it just went round the inside of that cave, do you? It's body went off in one direction, and its tail went off in the other.”

Dora thought of that huge body coiling through the darkness of underground tunnels, perhaps for miles.

“Perhaps it goes all the way round the outside of London,” speculated Adam, “like an underground M25.”

“Don't be silly. It can't be that big. Somebody would have found it by now.”

“We don't know how deep down it was.”

“It certainly seems like a very long way back up,” said Dora.

Their conversation came out in snatches and gasps, between the puffing and panting and grunts of effort with which they climbed upwards. They had already used up a good deal of energy running away from the snake, and now they had to keep stopping for rests. They were dripping with sweat, and neither of them wanted to carry the box any more, because they both felt that they needed their hands as well as their legs to help them climb.

“It can't be much further,” panted Adam. “If we were outside, we would have climbed a mountain by now.”

“I can't even remember what it's like outside,” said Dora. “It feels like we've been doing this forever. How long do you think we've been underground? Do you think it's been a whole day yet?”

“More like a week, if you ask me,” said Adam.

“I'm so thirsty again.”

“Don't talk about it. If you start to think about it, it makes it worse. Let's have another rest.”

“No, wait,” said Dora. She held the box up as high as she could. “Look – there's another arch.”


A few steps above them, just where the faint light from the box gave out, the stairway ended in a black opening. Tired as they were, they almost ran up the last part of the stair, and found themselves in another cave; but it was completely different to the one with the snake in it. As far as they could see by the light of the box, it was crammed with old bric-a-brac: bits and pieces of every possible description, some of them valuable but most of them not, thrown together in a horrendous jumble, stacked up high above their heads, and covered in dust and cobwebs. There were walking-sticks, pith helmets, books, dolls, carpets, bottles, pens, games of Monopoly, stuffed animals, false teeth, family photographs, toy trucks, maps, birthday cards, pram wheels, diaries, screwdrivers, umbrellas, plugs, pianos, old coins, kettles, picture frames, odd shoes, Gladstone bags, wooden legs, rocking chairs, someone's PE kit, and so on and so on and so forth and so forth – like the contents of the biggest, dirtiest and most badly-organised second-hand shop in the world.

There was a narrow path through the jumble, and they threaded their way along it as best they could. They often had to turn sideways to get through, and no matter how much care they took they were sometimes jabbed in the ribs by sticking-out chairlegs, or snagged on broken bits of wicker, or tickled by feather dusters. Eventually they came to the far side of the cave, where there was another archway: when they went through it they found themselves on a stair, leading upwards; and at the top of the stair was another cave full of jumble just the same as the first. In this way they slowly went up one stair after another, and through one cave after another, until they lost count. Dora thought they'd been through seven, but Adam said he was sure it was eight.

“Stop a minute,” said Dora.

“What?” said Adam impatiently. “Come on. I want to get out of here.”

“Look at this,” said Dora. She was brushing the dust off something which she had just taken from one of the piles of jumble. It was a home-made cloth doll, with woollen hair and glittery red shoes. “It's Dorothy from The Wizard of Oz,” she said.

“This isn't a toy shop,” said Adam. “You can't start carrying old dolls around.”

“Yes, but I recognise it,” said Dora. “It's mine. I lost it years ago.”


“It's the exact same one. Look – she's got a little tear in her skirt. I did that on a bramble in our garden. I lost her when I was about three.”

“It can't be.”

“But it is. And this isn't the only thing. I've been recognising stuff ever since we've been in these caves. There was an old Chinese fan back there -”

“Oh, never mind,” said Adam, moving on. “It must be a coincidence or something.”

“But Adam -”

“Sh!” He held up his hand. “Shut the box!”

“What? Why?”

“There's a light up ahead.”

She shut the box, and sure enough there was a gleam of reddish flickery light, shining through a chink in the jumble.

“What shall we do?” she whispered.

“We'll have to go and see what it is.”

“Are you sure?”

“We can't go back, can we?”

“No. All right.”

They crept forward – but it was a terribly difficult place to creep, without the light of the box. Gradually the reddish flickery light got stronger, and at last, peeping round the end of an upside-down sofa, they found themselves looking at a little fireplace with a hot red fire burning in the grate and an armchair next to it. The armchair had its back to them, so they couldn't tell if there was anyone sitting in it or not.

They stared in silence – but then Adam, leaning forward to get a better look, unconsciously put out his hand to steady himself, and touched the side of something smooth and cold. It might have been a china pot or a goldfish bowl. As soon as he touched it, he felt it wobble and slip. It must have been balanced on top of something else. Instinctively, he made a grab for it in the dark – but it was gone. His fingers closed on empty air. The next moment, whatever-it-was hit the floor and broke with a tremendous crash.

Up from the armchair jumped a tiny old man with a long pointy nose, huge ears and shiny black eyes.

“Aha!” he cried. “So, you're here at last! You took your time, I must say. I was starting to think the snake might have squashed you or something. Well – come along, come along. No point in lurking around in the dark like that. Come on out.”


Dora and Adam stepped slowly into the light. The tiny old man looked them up and down.

“Dear me,” he said. “Somewhat the worse for wear. Very dirty. Very down at heel.” He chuckled and rubbed his hands together, and something about the way he did it – very quickly, with his hands high up under his chin and his bright beady eyes shining – made both the children recognise him at once.

“It's you!” cried Dora, and “You were that mouse!” cried Adam.

“Yes, well, sometimes a mouse, sometimes a mouse,” said the tiny old man. “When it suits me. More often a squirrel. More convenient for getting up and down the tree.”

“What tree?” said Adam.

The little man looked at him sharply. “What a question!” he exclaimed. “Why, don't you know where you are? Don't you know what this is? This is Yggdrasil!”

“Yggdrasil?” said Dora. “What's Yggdrasil?”

“Oh, dear, dear, dear,” said the little man. “But I suppose I should have known. It's Urizen's fault, of course, all Urizen's fault. Yggdrasil is the world-tree, my dear... But if we're going to have explanations and stories, perhaps I had better sit you down and give you something to eat and drink.”

As soon as he said it, the children remembered how tired and hungry and thirsty they were: in fact they began to sway on their feet, and Dora thought she might be going to faint. But the little man bustled about, and within minutes he had found a padded stool with the stuffing coming out for Adam to sit on, and a painted chair with one rickety leg for Dora. Then he vanished into the darkness, and came back a couple of minutes later with a jug of water and a plate of apples and chestnuts and small potatoes. He put the chestnuts and potatoes on a shovel on the fire to roast, while the children gulped the water and wolfed down the apples; and although the apples were small and wrinkled and the water was served in chipped cups, they seemed like a delicious feast.

“Now then,” said the tiny little man, “first things first. Introductions. You may call me Ratatosk: and this is the place where I live, which is called Yggdrasil, or the world-tree. Its branches hold up the sky, and its roots hold together the earth.”

“How big is it?” said Dora.

“How would I know?” replied Ratatosk. “Too big to measure. Big enough to hold up the sky, and big enough to hold together the earth.”

“But then it would be huge,” said Dora, “and everyone would be able to see it, from almost anywhere. And I've never even heard of it.”

“That's because you've been living in Urizen's world, and Urizen has hidden the tree from you. But you may have heard about it without realising, because it's got lots of different names. Some people call it Yggdrasil, and some people call it the Tree of Knowledge.”

“I've heard of the Tree of Knowledge!” said Dora. “But I thought it was meant to be in the Garden of Eden.”

“Except that Mr Blake told us Urizen made that story up,” put in Adam.

“Well,” said Ratatosk impatiently, “I told you the tree's got lots of different names. There are also lots of different stories about it.”

“But how do we know which one to believe?” asked Dora.

“You could start by listening,” said Ratatosk sharply. “Instead of interrupting me before I can even get started.”

“Sorry,” said the both the children at once.

“All right,” said Ratatosk, regaining his composure. “Now, I'll tell you why it's called the Tree of Knowledge. The story goes that when Urizen first came to this world, he spent nine days and nine nights hanging upside-down from a branch of the tree by his foot, and staring into the abyss which lies beyond the edge of the world and underneath the tree's roots: and that was how he gained his wisdom. Then off he went and wrote down all his laws in a big brass book, and told everyone that they'd got to obey his laws, because he was the only one that really understood how things were, because he was the only one who'd looked beyond the edge of the world and into the abyss. And he didn't want anybody else contradicting him, of course, so he forbade anyone else to go near the tree, and eventually he cast a spell on them so that they couldn't even see it any more.”

“But how did hanging upside-down from the tree make him wise?” said Dora.

“You may well ask, my dear. Very good question, in fact. If you want my opinion, I don't think it did. I don't believe it made him wise at all. The only thing he found in the abyss was a reflection of himself – because the abyss is just a big empty space, when all's said and done, and you can't find anything in it unless you put it there yourself. Now, if Urizen had turned himself the right way up, and spent his time looking at the tree, then he might have really learned something.”

“But if everybody's forbidden to go near the tree,” said Adam, “what are you doing here?”

“Aha! Aha!” cried Ratatosk gleefully. He smacked his hands onto his knees, then rocked himself backwards and forwards in his chair, chuckling and shaking his head. “Well done, youngster! You've hit the nail on the head there! The thing is, he can't get rid of me! How he wishes that he could! Poor old Urizen! I get on his nerves like anything. But I'm part of the setup, I am. I was in the tree right from the beginning.”

“Then he didn't actually make the world,” said Dora. “If the tree was already here, and you were already here too.”

“Well, that's a moot point,” said Ratatosk. “Did he make the world, or did he find it ready-made? Nobody really knows the answer to that one: certainly not me. He believes that he made it, that's for sure, and that's why it annoys him so much when things go wrong. His creation keeps playing tricks on him, and he can't for the life of him work out why. But I know why.” He patted himself on the chest. “Me.”


Dora stared at him, and suddenly felt frightened. His eyes were very bright and his nose and chin were very pointy in the light of the fire: in fact he was rather devilish looking. “But you're not,” she said hesitantly, “you're not -”

He looked at her. “Not what, dear?”

“You're not the – you know, the – the bad -”

“The devil, do you mean? The great adversary? Satan? The prince of darkness? Beelzebub? Lucifer? Dear me, no. Do I look like it? I hardly know whether to be flattered or offended. Oh, no no no. Mine is a much more small-scale business altogether. No, no, I don't do really bad things. I just play tricks. A bit of jiggery-pokery here, a little bit of borrowing there – that's about the mark. You see, the branches and roots of this tree reach into all parts of the world. All parts of the world. And now that Urizen's made the tree invisible, nobody can see me coming and going.”

“So what do you do?” said Adam.

“Well – have you ever put something down, just for a moment; then turned away; and when you turned back again, the thing was gone? Vanished? And you couldn't find it, no matter how hard you looked?”

They stared at him.

“You mean – you steal things?” said Adam.

“I told you that was my old doll!” cried Dora.

“But what do you do it for?” said Adam.

“Oh, well, you know – it passes the time. It annoys Urizen. And it amuses me. But I don't just steal things, mind you. Sometimes very clever people make very clever plans, which ought to work perfectly, except that when they try them out something unexpected happens and everything goes wrong. That's usually me. And I put things back as well. Things sometimes turn up unexpectedly, in unexpected places, don't they? That's because I've put them there. And I also carry messages, in my own way.”

“Messages?” said Adam. “What sort of messages?”

“Well, I'm not the only one that lives in this tree. There are some other things that have been here for just as long as me. To start with, there's a big snake wound all round the roots, with its tail in its mouth, called Ouroboros.”

“Oh – we've seen it,” said Dora.

“I know you have. In fact if I'm not mistaken, you disturbed it in its sleep. I felt the tree shuddering and juddering an hour or two ago. That would have been about the time you were down amongst the roots, I should think.”

“We're sorry,” said Dora. “We didn't even know the snake was down there. At least, we didn't know it was a snake. And we were so thirsty -”

“So you went down to the pool,” said Ratatosk.

“Yes,” said Adam, “and then when we saw the snake, or realised what it was, it gave us both such a shock that we shouted out -”

“- and then it started to wake up,” said Dora.

“So we ran for our lives,” said Adam.

Ratatosk chuckled. “I bet you did,” he said with a grin. “But you needn't have worried. He was only stirring in his sleep. He does it from time to time. I don't expect it was anything to do with you, not really.”

“Oh!” said Dora.

“No, no. A little bit of shouting from the likes of you two wouldn't be enough to wake him up. But all the same, his stirring is a bad sign. He does it more and more often these days. He's not sleeping as soundly as he used to.”

“Isn't he?” said Dora. “Why not?”

“The warmth, my dear. It's getting too warm for him down there.”

“But it was freezing!” said Adam.

Ratatosk shook his head. “I daresay it seemed like that to you. But there never used to be a pool down there, or a drip to feed it. The ice used to be thicker, too. Then along came Urizen, with his mines and his forges, his mills and his factories, and his cars and his airoplanes: burning and building, building and burning, making the world warmer and warmer bit by bit. After a while the ice began to melt, and Ouroboros started to stir in his sleep. And I should warn you, children, that if he ever wakes up, and lets go of his tail -”

He snapped his fingers.

“What?” said Adam.

“The end of the world,” said Ratatosk.

The children stared at him in disbelief.

“What, really?” said Dora.


“But why would it be the end of the world?” said Adam.

“What have I been telling you?” cried Ratatosk. “The world tree holds up the sky with its branches, and holds together the earth with its roots. All around the roots of the tree is Ouroboros, winding in and out, asleep with his tail in his mouth. If he wakes up, and starts to wriggle about, all the roots will be broken. The tree will die.”

Dora felt as if someone was squeezing her heart. It couldn't be true, could it? Perhaps Ratatosk was just having a joke with them. He certainly didn't seem particularly bothered. He was smiling and rubbing his hands together.

“But... but... can't anyone do anything about it?” said Adam.

“Of course they can,” said Ratatosk. “You're doing something already. That's why I'm helping you.”

“Us?” said Dora. “What are we doing?”

“You're trying to solve the puzzle in your box.”

“But we're doing that to wake my Dad up! How does that stop the world from getting warmer?”

“Oh, it's all part of the same thing. You'll find out, when you get to the end of the puzzle. Perhaps you will, anyway. Puzzles can have more than one answer, you know, just as things can have more than one name, and stories can be told in more than one way. Urizen would like everything to be fixed and single, but it isn't. Look,” he added, giving the shovel a rattle, “the chestnuts and potatoes are ready. I'll fetch the bread and butter.”


He jumped up, and disappeared into the jumbled darkness of the cave. Dora looked round cautiously, to make sure that he was gone.

“I don't understand what he's saying,” she whispered. “Do you?”

“I think he's a bit barmy,” said Adam, pulling a face.

“Do you think it's true, about the world coming to an end?”

This time Adam pulled a different sort of face. “I hope not,” he said. But she could see that he was worried. And she remembered how terrifying it had been when the snake started to move.

Ratatosk came back with the bread and butter. It was home-made bread, which he cut into thick slices, and then spread on the butter (equally thickly) with the end of the breadknife. Then he peeled the chestnuts with deft movements of his fingers, apparently not burning himself, even though they were glowing and smoking like hot coals. He passed them round, along with the potatoes, which were half burnt down one side and half raw down the other. Even so – and even though they were still worried by what he had said about the end of the world – the children found the hot food even more delicious than their first course.

“Weren't you saying something about being a messenger?” said Adam, when he only had a few bits of chestnut and a crust of bread left to eat.

“Ah yes,” said Ratatosk. “The messages. Well, at night-time, when the sun goes down and the Queen of the Night takes to the air, a black beetle comes down from the sky, crawls into the caves underground, and begins to gnaw at the world tree's biggest root.”

“A black beetle?” said Adam, in a frightened voice.

“Yes, a black beetle. It gnaws at the root all night long, while the Queen of the Night holds court in the sky and her owls fly from the tree to the moon and back again. But in the morning, the Queen of the Night returns to her upside-down palace underneath the earth, her owls come to roost in the branches of the tree, and the beetle crawls off; and during the day the tree root grows back, so that by the time the sun goes down again it is as thick and strong as ever.”

“Where does the beetle go?” said Adam.

“Some say it goes up into the sky, and some say it crawls about the world, creeping up behind people and nipping them with its pincers when they least expect it.”

Adam shivered.

“But I dress myself up as a squirrel,” said Ratatosk, “and I run up into the branches of the tree and torment the owls when they're trying to sleep. I tell them I've brought them a message from the beetle: he's gnawing at the root of the tree, and when his work is done there will be nowhere for them to perch, and they will have to go and live on the moon. Then at night-time I run down to the beetle and speak to him while he gnaws the root. I tell him that the owls have warned the Queen of the Night about him, and she is coming to tie him to a pin by a thread.”

“Tie him to a pin by a thread?” repeated Dora. Of all the peculiar things Ratatosk had told them, this struck her as the most peculiar of all.

“Yes,” replied the little man, “but if he hears me, he never gives any sign. He just keeps gnawing away at the root. Well,” he added abruptly, getting up from his armchair, “I see that you have finished your food, so it must be time for us to go.”

“What do you mean?” said Dora. “Where are we going?”

“I'm taking you up to the owls,” said Ratatosk. “And they will take you to the moon.”