Coraline shrugged. "Okay," she said. "It's a deal."

She ate the breakfast, trying not to wolf it down. She was hungrier than she had thought.

As she ate, the other mother stared at her. It was hard to read expressions into those black-button eyes, but Coraline thought that her other mother looked hungry, too.

She drank the orange juice, but even though she knew she would like it she could not bring herself to taste the hot chocolate.

"Where should I start looking?" asked Coraline.

"Where you wish," said her other mother, as if she did not care at all.

Coraline looked at her, and Coraline thought hard. There was no point, she decided, in exploring the garden and the grounds: they didn't exist, they weren't real. There was no abandoned tennis court in the other mother's world, no bottomless well. All that was real was the house itself.

She looked around the kitchen. She opened the oven, peered into the freezer, poked into the salad compartment of the fridge. The other mother followed her about, looking at Coraline with a smirk always hovering at the edge of her lips.

"How big are souls anyway?" asked Coraline.

The other mother sat down at the kitchen table and leaned back against the wall, saying nothing. She picked at her teeth with a long crimson-varnished fingernail, then she tapped the finger gently, tap-tap-tap, against the polished black surface of her black-button eyes.

"Fine," said Coraline. "Don't tell me. I don't care. It doesn't matter if you help me or not. Everyone knows that a soul is the same size as a beach ball."

She was hoping the other mother would say something like, "Nonsense, they're the size of ripe onions-or suitcases-or grandfather clocks," but the other mother simply smiled, and the tap-tap-tapping of her fingernail against her eye was as steady and relentless as the drip of water droplets from the tap into the sink. And then, Coraline realised, it was simply the noise of the water, and she was alone in the room.

Coraline shivered. She preferred the other mother to have a location: if she were nowhere, then she could be anywhere. And, after all, it is always easier to be afraid of something you cannot see. She put her hands into her pockets and her fingers closed around the reassuring shape of the stone with the hole in it. She pulled it out of her pocket, held it in front of her as if she were holding a gun, and walked out into the hall.

There was no sound but the tap-tap of the water dripping into the metal sink.

She glanced at the mirror at the end of the hall. For a moment it clouded over, and it seemed to her that faces swam in the glass, indistinct and shapeless, and then the faces were gone, and there was nothing in the mirror but a girl who was small for her age holding something that glowed gently, like a green coal.

Coraline looked down at her hand, surprised: it was just a pebble with a hole in it, a nondescript brown stone. Then she looked back into the mirror where the stone glimmered like an emerald. A trail of green fire blew from the stone in the mirror, and drifted towards Coraline's bedroom.

"Hmm," said Coraline.

She walked into the bedroom. The toys fluttered excitedly as she came in, as if they were pleased to see her, and a little tank rolled out of the toybox to greet her, its treads rolling over several other toys. It fell from the toybox on to the floor, tipping as it fell, and it lay on the carpet like a beetle on its back, grumbling and grinding its treads before Coraline picked it up and turned it over. The tank fled under the bed in embarrassment.

Coraline looked around the room.

She looked in the cupboards and the drawers. Then she picked up one end of the toybox and tipped all the toys in it out on to the carpet, where they grumbled and stretched and wiggled awkwardly free of each other. A grey marble rolled across the floor and clicked against the wall. None of the toys looked particularly soul-like, she thought. She picked up and examined a silver charm-bracelet from which hung tiny animal charms which chased each other around the perimeter of the bracelet, the fox never catching the rabbit, the bear never gaining on the fox.

Coraline opened her hand and looked at the stone with the hole in it, hoping for a clue but not finding one. Most of the toys that had been in the toybox had now crawled away to hide under the bed, and the few toys that were left (a green plastic soldier, the glass marble, a vivid pink yo-yo, and such) were the kind of things you find in the bottoms of toyboxes in the real world: forgotten objects, abandoned and unloved.

She was about to leave and look elsewhere. And then she remembered a voice in the darkness, a gentle whispering voice, and what it had told her to do. She raised the stone with the hole in it, and held it in front of her right eye. She closed her left eye and looked at the room through the hole in the stone.

Through the stone, the world was grey and colourless, like a pencil drawing. Everything in it was grey-no, not quite everything. Something glinted on the floor, something the colour of an ember in a nursery fireplace, the colour of a scarlet-and-orange tulip nodding in the May sun. Coraline reached out her left hand, scared that if she took her eye off it it would vanish, and she fumbled for the burning thing.

Her fingers closed about something smooth and cool. She snatched it up, and then lowered the stone with the hole in it from her eye and looked down. The grey glass marble from the bottom of the toybox sat, dully, in the pink palm of her hand. She raised the stone to her eye once more, and looked through it at the marble. Once again the marble burned and flickered with a red fire.

A voice whispered in her mind, "Indeed, lady, it comes to me that I certainly was a boy, now I do think on it. Oh, but you must hurry. There are two of us still to find, and the beldam is already angry with you for uncovering me."

If I'm going to do this, thought Coraline, I'm not going to do it in her clothes. She changed back into her pyjamas and her dressing gown and her slippers, leaving the grey sweater and the black jeans neatly folded up on the bed, the orange boots on the floor by the toy box.

She put the marble into her dressing-gown pocket and walked out into the hall.

Something stung her face and hands like sand blowing on a beach on a windy day. She covered her eyes, and pushed forward.

The sand-stings got worse, and it got harder and harder to walk, as if she were pushing into the wind on a particularly blustery day. It was a vicious wind, and a cold one.

She took a step backwards, the way she had come.

"Oh, keep going," whispered a ghost-voice in her ear. "For the beldam is angry."

She stepped forward in the hallway, into another gust of wind, which stung her cheeks and face with invisible sand, sharp as needles, sharp as glass.

"Play fair," shouted Coraline, into the wind.

There was no reply, but the wind whipped about her one more time, petulantly, and then it dropped away, and was gone. As she passed the kitchen Coraline could hear, in the sudden silence, the drip-drip of the water from the leaking tap, or perhaps the other mother's long fingernails tapping impatiently against the table. Coraline resisted the urge to look.

In a couple of strides she reached the front door, and she walked outside.

Coraline went down the steps and around the house until she reached the other Miss Spink and Miss Forcible's flat. The lamps around the door were flickering on and off almost randomly now, spelling out no words that Coraline could understand. The door was closed. She was afraid it was locked, and she pushed on it with all her strength. First it stuck, then suddenly it gave, and, with a jerk, Coraline stumbled into the dark room beyond.

Coraline closed one hand around the stone with the hole in it and walked forward into blackness. She expected to find a curtained anteroom, but there was nothing there. The room was dark. The theatre was empty. She moved ahead cautiously. Something rustled above her. She looked up into a deeper darkness, and as she did so her feet knocked against something. She reached down, picked up a torch, and clicked it on, sweeping the beam around the room.