‘What are you doing, Tiaan? Why are you standing there like that?’ came Haani’s voice from behind.

‘Shh!’ Tiaan could not answer lest she lose her concentration. It was coming, it was coming! The crevasse cracked open. She drew power from it, clumsily. It had no perceptible effect on the glacier but Tiaan felt a surge of cold force stronger than anything she had handled before. It flowed into the amplimet, the spark lit up like a flash of lightning and Tiaan pushed hard.

The opposing force gave before her like a knife thrusting through a drum. She fell, almost crashing into the glass doughnuts. Regaining her balance, she slipped the amplimet from the globe, jammed it into the basket and banged the amber door.

The glow and the whine reappeared. The barrier came up so hard and fast that Tiaan was sent skidding twenty paces across the room. Fortunately there was nothing to crash into or she would have broken bones.

She lay dazed as Haani came screaming up. ‘Tiaan, are you all right?’

Tiaan got up, with the child’s help. ‘I think so.’ She dusted herself off, only to discover that the slide had torn a hole in the knee of her beautiful pantaloons. Not a large one, but it made her look like an urchin, rather than a beautiful woman rushing to meet her lover.

No time to change. The doughnuts were now dazzlingly bright, the amplimet glowed like a furnace through the walls of the basket, while tight beams of coloured light pulsed out of random parts of the device. The noises coming from it ranged from shrieks to barely audible rumbles. Every so often the whole machine vibrated as if to shake itself apart, and the twisticon was lit up by pulses of green light that formed standing waves inside.

‘I’ve got to do it now, before it breaks.’ Squatting down, Tiaan worked the beads in their orbits for what she hoped was the last time.

‘Minis, Minis, where are you?’ Blankness, struck through with brilliant beams of light. ‘Minis. Come to me. The port-all is built. It’s ready to bring you to safety.’

Still nothing. She ran through her memories of all the times she’d contacted him before. Suddenly she smelt smoke.

‘What are you doing, Haani?’ She could not look or she would lose it all.

‘Just sitting here,’ came a small voice beside her.

‘You’re not burning anything?’

‘Of course not!’ the child said indignantly.

‘It must be Aachan!’ Tiaan said to herself. ‘It has to be. Minis!’ she roared, and there it was, a great dome of an island, upon which lava flows were advancing, boiling the sea to steam.

On the ash-layered top she saw people in their thousands, sheltering under steep roofs collapsing under the weight of ash and cinder. Others huddled in the mouths of caves. Jagged volcanic bombs rained from the sky, some bursting open to reveal liquid interiors. Everywhere people were screaming, weeping, dying. She caught a stinging whiff of brimstone.

Her viewpoint drifted up a slope. A tower appeared, made up of dozens of slender spires, the sides of which were clustered with shiny silver buttons, or domes, or bowl-shaped caps. They must have been huge, for around the spires a road spiralled its way to the very top. The road was suspended from the towers by cables that from this distance looked as thin as hairs. At the top stood a metal plate the twin of the one on the wall behind her.

What on earth was the structure? Could it be their end of the gate? It must be, though the winding road just ended at the top. ‘Minis!’ She did not know that she had screamed it aloud. ‘Minis, tell me what to do!’

It’s Tiaan!

Just a whisper, but it made her skin shiver. She was going to succeed after all. ‘Minis, I’ve done it. I’ve made the port-all – the zyxibule.’ That word felt unlucky. ‘Tell me what to do.’

Why did you not call us, Tiaan?

She could not see him among the throng. How she wanted to. ‘I called many times. You did not answer.’

No matter. It’s too late. We can’t open the gate, Tiaan. We’re too weak now.

‘There’s power here. I can channel more if you need me to. Tell me how. I can make the gate from here.’

Voices were arguing; some she recognised. The harsh tones of Vithis, Minis’s foster-father. The calm, resigned voice of Luxor, and Tirior urging them on, to seize the opportunity.

What have we to lose? said Luxor. We’re going to die anyway.

I say we trust her, said Tirior. Tiaan has taken on every challenge so far, and succeeded against our expectations.

And if she fails? grated Vithis. We don’t die a noble death on beloved Aachan – we die trapped in the hideous void, to be eaten like carrion. Where is the dignity in that?

Then stay behind! roared Luxor. Go to the Well of Echoes and die with your precious dignity! I choose life for my clan.

And I, said Tirior. The Ten Clans have agreed on it.

I don’t like it, said Vithis. To offer such a secret to an old human, and one who is barely out of childhood. What will she do with it?

Time to worry about that if we survive, said Tirior.

Yes, said Vithis. And we will worry, you can be sure.

They voted and it was agreed. They would make the attempt. Minis came back and told Tiaan what to do.

Tiaan felt panicky to see the Aachim crammed there, dying. Their lives relied on her. She understood little about the deadly geomantic Art she would have to wield and get absolutely right the first time. If the great Aachim were afraid of the consequences, how could she hope to succeed?

But she had to. Her fingers worked desperately and Tiaan hurled her senses outward, skipping over the little glacier she’d used before. She needed a lot of power now. West she sped, to pick up the enormous glacier grinding down from the Tirthrax ice cap. It was the fastest of all – Tiaan imagined that she could hear it grinding in its bed. Yet even that pace was no faster than the creeping of a snail. The wait was agonising.

Where the glacier curved around the edge of the mountain toward the icefall, a fracture would open up from one side to the other. She could already see its field, like a concave lens. With desperate recklessness she seized upon the opening crevasse and took out every bit of power she could.

Ice screamed as it was torn apart and a paralysing cold rushed through her. Tiaan felt as if she had frozen solid. The whole port-all shuddered, exploding with light and sound. She thought it was going to tear itself apart.

The mountain shook. There came a noise like boulders being crushed and something went boom, so loud that her ears hurt. After that she heard nothing at all.

Haani was tugging desperately at her hand. ‘Tiaan, say something!’

Tiaan picked herself up from the floor, feeling that a long time had passed. Her vision of Aachan had disappeared. Lightning forked from the amplimet basket to the metal plate on the back wall. The glass doughnuts went out. After an instant of utter darkness the glow reappeared. Aachan was back, too.

A monstrous curving lens flashed into being at the very top of the road winding up from those spiked towers. For an instant she saw Tirthrax reflected on the lens. It must have been a reflection, for it was a mirror image, the toe of the glacier falling off the wrong side of the mountain. Tirthrax was the other way around.

A star appeared in the centre of the reflection, then a hole blasted right through the lens. There were screams and hoarse cries as an avalanche of snow erupted through, to the incredulity of the Aachim. It was like a white umbrella that melted in the hot air and fell as blessed cold rain.

The gate! The gate is open! she heard the multitude cry.

Hurry! Before it closes again.

People raced to machines that looked like clankers. Briefly she saw Minis’s face, and those others she had seen before – the ones who knew all about the gate.