Her left hand clutched at stone which broke off, but her right hand found something firm. She felt her body swing round and slam into the outside of the wall, the force of it coming so close to making her lose her grip that she expected to fall. But her clenched hand stayed where it was while she scrabbled with her left to find something else to hold.

Her fingers snagged on something and clutched on, a precarious grip on a bump in the stone that didn't feel it could hold up against the wind tearing at her. And the breeze was so cold that her fingers began to burn with it and she knew they would start to go numb soon.

You have to find a foothold, she thought, remembering climbing at Lake Placid leisure centre with Dad. Your arms aren't strong enough to take your weight. But her legs were hanging in air, and when she looked down she saw that the room hung free of its surroundings, with nothing below it. Her lower legs were dangling beneath its floor, and there was nothing between her and a level far below.

Her eyes were drawn down further, to the kingdom thousands of feet below, and she watched it spin sickeningly. She couldn't quite believe she was here, her hands holding her above a drop that she could never survive. It was like so many of her bad dreams, where she woke up in a rush of terror as she began to fall, that there was a feeling that this couldn't be real.

Her left hand moved as the lip of rock she clutched fractured and started to pull away.

No, she thought. That isn't fair!

As she tugged off her straining right arm muscles and found another grip, she realised that the link was no longer working, and that meant that the magic of the tower was failing. It was crumbling away with nothing to hold it up.

How long will these rooms stay up without it? She thought, but it was too much to worry about right now. She had to survive, and right now that seemed almost impossible.

She tried to heave herself up and back into the room, choosing immediate survival over the threat of standing in front of the mage again. But she simply wasn't strong enough. She had never managed to complete a pull-up at the gym, even with a proper bar to hold on to instead of a tenuous and awkward grip on crumbling stone.

Her arms began to burn with the effort just of keeping there, and she knew she had moments in which to do something. She looked down at her feet again and wondered if she could swing one of them upwards and find a toe-hold.

And then, drifting in the air below her feet, she caught sight of the blue-white magic of one of the intention winds. In a rush, she remembered the little threads of light that had seemed to connect the tower as she had looked at it from a distance. Of course there had to be intention winds between the rooms that weren't properly connected with the rest of the tower; winds that hung out in the air and must be terrifying to use.

Though using them would be far less terrifying than what she now realised she was going to do: to let go and try to fall into one.

It wasn't close to her, she saw, as she craned her head as far as she could without losing her grip. She would have to swing herself under the room if she was going to reach it. And it might be further away than it seemed from this angle. She had no real way of telling.

Which symbol had she used to call the travelling wind before? Summoning?

She couldn't remember it. With the pain in her arms and the cold wind knifing through her, she couldn't bring anything to mind except the drop below her.

She squeezed her eyes shut, and willed herself to bring to mind the last page of the book, with its diagram of all thirteen of the symbols laid out in a circle with the symbol of wholeness at the centre. She had pored over it in Afi's hut, and glimpsed it again and again since.

You have to be able to remember! She thought. But she was exhausted, and hurting, and terrified. Beyond her fear of falling, she was afraid of the mage coming to find her again, and crushing her without even trying.

A feeling of warmth spread across her skin, and she blinked her eyes open again to see the stone in front of her face lit a warm, orange-yellow. It was almost sunset, she realised, and the sun had dropped low enough at long last that it was free of the cold mage's conjured storm.

The wind lifted her hair and drew shadows on the stone, and just for a moment she saw a half-circle there, and it released a rush of memory.

It's a simple symbol, she thought. So simple.

She held an image of a half-circle with a line drawn through it in her mind and put the ragged remains of her tired will behind it. She saw the intention wind begin to move below her, and she realised that she would need Ruidic there, like the book had told her.

The answer came quickly, this time. She had seen enough of the cold mage's mind to understand him.

"Ruidic!" she shouted. "You need to go to the garden! The weapon is there, and you're the only one who can release it! Go to the garden, Ruidic!"

She didn't know if she would have been able to make herself let go if the firm hand-hold under her right-hand hadn't broken off. As she felt herself lurch, she swung her feet forwards and under the room and let go with her left, clumsily, her arm scraping down the jagged stone.

For awful, endless seconds, she simply fell, and the terror was so great that she couldn't think about anything except that fact that she was falling. She felt as though she'd fallen miles by the time the rushing intention wind enveloped her, and slowed her, and then whisked her down and away from the room and the mage.

The garden, she thought. Take me there, quickly. Please.

The wind seemed to read and understand. She began to pick up speed again, and suddenly she was out of the brilliant sunlight and in a dim tunnel bored through the stone of the tower. And then she was hurtling through rooms too quickly to see anything but blurs, until she was rising up again and then with a soft feeling around her she slowed to a stop and was deposited gently on the grass of the garden.

Time was everything now. She understood that. She had stopped it once before, but she understood that it had been with Ori's help.

"Can you help me now, Ori?"  she muttered, but there was no answering sound, and the room was quiet in the evening sunlight, and empty of those gleaming lights.

The book had told her to go here. But what was it she was supposed to see?

You have already seen...

She glanced at the crystal spire above, but then looked away again. It was nothing but worked stone, however beautiful and spectacular. She knew it didn't hold the answer. It was a living spell she needed to cast.

She began to walk through the garden, looking instead at the gorgeous plants Ruidic had created. She saw the hot pink flowers she had stood beside with Afi, and pushed away the immediate rush of fear for him. There was no time now.

A dragon-fly buzzed over to her and settled for a moment on her left arm. It was only as it landed that she looked properly at her skin and realised that she had scraped most of it off as she fell. It throbbed with pain now that she saw it, but she pushed that away too, and focused for a moment on the dragon-fly.

She looked at its jewelled workings, and felt as though something were pushing at her mind.

They aren't living, are they? She thought. How can they be the answer?

The dragon-fly took a few steps, its feet as light on her skin as if it had been a real creature, and then lifted into the air and buzzed away. Feeling a frustrating sense of still  missing something, even after understanding so much, she trod onwards.

It shocked her when she rounded a stand of trees and saw the burned area of the garden again. She was here to think of life, and right in front of her was evidence instead of destruction she had wrought whilst trying to save the kingdom.

The warmth of the garden was lessened here, and she shivered in it, still chilled to her core from being outside in the arctic air. She realised that there was a gap in the crystal above, where it had melted, and it was letting in a draught of cold air and a sprinkling of snow.

She walked away from it, more urgently, and ducked under the burned and lifeless branches of a tree. She had come to the edge of the crystal dome, and was looking at the kingdom again.

She looked down at Kryzna first, tracking around it with her eyes until she could see the swathe of destruction that the mage had brought with him. But there was no life there, was there? she thought, feeling a familiar sickness in her stomach. It was death he had brought with him.

She blinked, then, as she saw movement. It was a tiny pair of forms, but they were people, unmistakeably alive, and making their way through the rubble.

There is life there, she thought, and it gave her another brick of hope to lay down in the face of the waves of hopelessness that came with every encounter with the cold. There are people to save.

And then as she looked further out into the kingdom, she saw more movement. There was a black cluster moving across the snowy plains, and as she squinted at it, she saw that it was a crowd of people. Trying to make sense of it, she drew into her mind the symbol of revealing, seeing it easily as she held in her head that last page of the book. It was half an eye, now that she thought about it, the spreading lines the lashes, and on the diagram she recalled it sat where the number nine would have been on a clock.

With her will behind the symbol, her view suddenly rushed in and sharpened on the moving black cluster, and she saw that it was an army of men and boys, carrying swords like those Roschan's men had held and bearing a broken circular crest with a jagged line scored through it. They were marching northwards towards Naian, the westerly city of the kingdom, and as she moved her gaze that way, she saw more movement.

A cold feeling spread through her, all but overwhelming the foundations of hope and optimism she had laid down.

Do you want to see it? The mage had asked, and she did see it now. She saw the army he had boasted about, that he had come ahead of. It was visible beyond the wall, and the snowy plains beyond it had been turned black and green and grey and brown for a square mile with the forms of flesh wolves, evanescents and nightmares – and with other forms that her magically sharpened sight didn't recognise: creatures that writhed through the air, or crawled across the ground.

The army was vast. There must have been tens of thousands - hundreds of thousands of creatures there, and the men coming to face it numbered, what, a few thousand? She had little way of telling but the black crowd covered so much less ground that it was obvious they wouldn't stand against the oncoming force for minutes, never mind defend the city against it.

She could see how it would happen, how it would swarm over the walls and take Naian; and then how it would spread out through the Kingdom, from city to city, killing as it went.

And there would be people in Naian. She focused her gaze on the city, and saw them running through the streets, creating makeshift barricades that couldn't do them any good, but still struggling and trying.

It made her ache and burn to help them, but as she looked, she had that feeling of something just beyond her reach again. She frowned in furious concentration at the city, and the people living within it; at its silver-grey, sturdy buildings and its orderly streets that fanned out from the wall.

What was it she was missing? She wanted to strike her head against the crystal in frustration. It was there, she just needed to see.

And all at once, she did see. She saw the streets of the city, with the broadest boulevards seeming to cut it up. She saw how the first and longest of them was a semi-circle that matched the curve of an open, circular park next to the wall. She saw how the other boulevards radiated out from that semi-circular street, looking like the lashes of an eye that had been cut in half cross-ways, and she knew that she had seen that pattern before in her mind mere seconds ago.

The sense of understanding was like a deep, resonating bell sounding within her mind. She knew that she was right, and it was only to confirm it that she looked northwards to the city of Jiescek and traced in its streets a circle with a jagged line cut through it. She remembered drawing the shape in the snow the first night she had arrived in the Cold Lands, and she felt a smile forming on her lips.

She heard movement, and knew that it was Ruidic. She hoped that he would be alone, though she had no way of being sure. Before she went to find him, she looked at one final city, the city of Osciem which stood some miles south of Naian and further around the wall. She didn't really need to look at the streets, when she had seen the broken version of the circle with a line cut through it – the symbol of breaking – on the crest of the army coming from the city. But she traced the streets with her eyes anyway, feeling strength and certainty grown in her as she followed the familiar lines.

She heard a crashing, rushing sound of movement through the undergrowth, and turned as Ruidic arrived. He was alone, as she had hardly dared to hope he would be, which meant that she had time enough to work the spell.

He stopped in front of her, breathing deeply, and then his mouth twisted into the familiar smirk. "Idiot stepped into the intention wind with me. You would have loved the look on his face as the wind wrapped itself around him and carried him the other way. You'd think he'd have done his homework about this place and used the stairs."

Grace beamed at him. "I was hoping you might travel that way. If anyone meant harm to the city, it's him." And then she nodded at him. "I don't think the dungeons will hold him for long, though. So we'd better work fast."

"Cartheno's Fire, eh?" he asked, quizzically, and she laughed.

"No, Grace's Fire," she said. "There's no weapon here yet. But I'm going to make one."

He shook his head slightly, but she understood that it was admiration and not disagreement. She should have known that the best way to please him would be a display of arrogance.

One of Ruidic's dragon-flies buzzed past her ear, making her jump, and then alighted on Ruidic's hand. He held it out, and looked at the little creature for a moment, with a smile quite different from the one he had worn a moment ago. He glanced past her at the burned garden, then, and she saw the pain on his face.

Bring Ruidic with you... she thought, and with a slightly hollow feeling, the final piece of this elaborate puzzle fell into place.

She walked slowly over to him, and lifted his hand to look at the tiny dragon-fly. It was perfect, and lovingly-crafted; and as she looked at it, it twitched its metallic wings, and then took off to begin its flight again, made of jewels and metal but unmistakeably alive.

A beautiful song rang out, one of his created birds, and it almost seemed to laugh at her while it confirmed that she was right.

"No," she said, quietly. "Not Grace's Fire. Ruidic's Fire. I'm not going to save everyone. You are."