The thapter shot sideways. Had someone fired on them? Nish couldn’t tell. Malien whipped around in a circle and behind the air-dreadnought hovering over the tower. It dropped three rocks, one after another, as he fired his javelard at the rotors. He only had to hit one to disable the craft and felt sure he would, having done it before. Unfortunately the air-dreadnought rose suddenly as the weight was released, and his spear passed harmlessly below its keel.
Nish cursed and wound his cranks furiously. It took so long to reload. His eyes followed the rocks towards the tower. They seemed to be heading directly for it. He held his breath. One puff of dust rose beside the tower, and two more down the slope of the peak. Hitting the target must be harder than it looked.
The air-dreadnought moved off, though it was as slow as a tortoise compared to the thapter in Malien’s nimble hands. Nish took careful aim at the port rotor and pulled the lever. At this distance he couldn’t miss, and didn’t. The rotor shattered to splinters, some of which flew into the starboard rotor, destroying it as well. The pilot pulled the floater-gas release rope and the air-dreadnought dropped sharply away to the south.
Malien shot away, carving a wavy trail across the sky to avoid one of the thapters. Judging by the reckless skill with which it was being flown, Chissmoul was at the controller.
Nish felt a surge of pride at the prowess of his young pupil, until he realised that she was now an enemy trying to bring him down. He mechanically loaded another spear as he searched the sky.
The other air-dreadnoughts were hovering some distance away, waiting to see what happened. The thapters approached, one on either side, and Kattiloe was the other pilot. Nish had chosen them both, supervised their training and helped them through dozens of crises. He liked Kattiloe and Chissmoul. Moreover, for the past hundred and fifty years, women of childbearing age had been protected at all costs, for the survival of humanity. In a battle with another thapter, there was little to do but attack the pilot, but Nish wasn’t sure he could fire his javelard at a woman. Shooting Chissmoul or Kattiloe was unthinkable. He wondered if they felt the same. Probably not – men weren’t precious, especially not traitors like him. They would follow Orgestre’s orders and do their duty.
The thapter lurched, tilted sideways, dropped sharply then stopped in mid-air as if it had landed on a mattress.
‘What the blazes is that?’ Malien yelled.
Had something gone wrong with the field? Were they going to fall to their doom as the lyrinx had earlier? Bile froze in his throat. Malien was looking out to the left. He followed her out-flung arm.
A dark mass like a whirling funnel, or a tornado, had just slipped over the horizon. The funnel was black at the bottom, paling upwards to grey with flecks of yellow, and it was moving steadily across the bed of the sea in their direction.
‘It’s the Well, grown monstrously large,’ he said. ‘It looks as if it’s coming out of the ground, growing above it as well as below.’
Malien could not have heard him over the wind. ‘It’s the Well,’ she called.
‘What’s it going to do?’
‘I don’t want to know.’
In the tower, an hour or two had gone by but Tiaan still hadn’t worked out how to open the box. The sapphire rod was useless. It may well have been a key but there was no lock to put it in. Frustrated, she banged the box with her fist.
‘Perhaps it’s not meant to be opened,’ said Gilhaelith. ‘Can you use it without doing so?’
‘I can’t tell. I don’t understand anything, Gilhaelith. If this is the port-all, it’s completely different to the one I used at Tirthrax. That one filled a room and had hundreds of parts, but there doesn’t seem to be anything to this one. The box weighs nothing. It’s as if it’s empty.’
‘Keep trying,’ said Gilhaelith. ‘Irisis, what’s going on outside?’
Irisis tucked her spyglass under her arm. ‘I can see the end of the lyrinx column.’
‘That’s something. Go down and find out how close the leaders are, before it gets dark.’ Gilhaelith turned to Tiaan. ‘What if you were to touch the sapphire to the box?’
‘I’ve already tried.’ Tiaan showed him what she had done, touching the smooth stone to the faces, the edges and the corners. Nothing happened. The box was so perfectly built that there was not a seam visible. It looked as if it had been made in one piece.
Gilhaelith wandered over to the window and cried, ‘Oh, it’s beautiful; just beautiful.’
Tiaan put the sapphire down on the box and ran across.
‘It’s the Well,’ said Gilhaelith. ‘It’s coming right at us, like a geomancer’s dream.’
‘You don’t have the kind of dreams I do,’ Tiaan muttered. ‘Vithis said that all Santhenar would rue the day. Do you think he’s sent it at us?’
‘Not after he’s dead.’
‘It’s a bit of a coincidence that it’s coming straight for us, then.’
‘The node might be attracting it.’
‘What will the node do to it?’
‘Who knows? Make it stronger, probably.’
‘And if the Well meets the gate?’
He looked at her, opened his mouth, closed it again.
‘Gilhaelith?’
‘I wouldn’t like to imagine the consequences.’
‘Keep an eye on it.’ Tiaan didn’t know why she’d said that. Nothing could influence the path of the Well now. If it came, it came. Was it possible Vithis had set it to consume everything on Santhenar?
She raced back to the box, to discover that it had opened like a black flower, the front face drawing seamlessly inside. How had that happened? All she’d done was lay the sapphire down on top.
She looked in, but it was so black that she couldn’t see the sides. Tiaan rotated the box towards the light and her head spun, just like the time at Snizort when she’d looked into the tesseract and the incomprehensible fourth dimension had exploded all around her. Was this box another tesseract – a cube in four dimensions?
Taking the amplimet in hand, she tried to create a mental map of the inside. It should have been as simple as imagining the walls of a black cube, but it wasn’t. The walls kept shifting when she concentrated on them.
‘Just one at a time,’ said Gilhaelith, putting a hand on her hand.
Did he have any idea what she was trying to do? Tiaan supposed that he must. She fixed the left wall in her mind and attempted to attach the others to it, which was easier, though the walls still seemed to move around.
‘Now what?’ she said, looking up to him for advice.
‘Perhaps it’s all in the mind,’ he said absently. ‘I’m going below.’
‘Whose mind? Vithis’s? Yours? Mine?’
He was gone. Tiaan imagined passing through the rear wall of the cube and found herself in another space exactly like the original one: a cube attached to a cube, though she could not visualise how it connected to the first. She fitted it to her mental map anyhow and went through the right-side wall to another cube, which led back to the first. She recognised it because one wall was open and she could see her face staring in. The thought made Tiaan so dizzy that she fell off her chair.
Had Vithis been lying when he gave Malien the key? She didn’t think so, but how could she tell? He’d deceived and manipulated her from the beginning.
Maybe the gate was all in the mind, and the way would only become clear if she could imagine the unimaginable – the hypercube the way it really existed.
Tiaan recreated her mental image, passing through the black walls into cubes which only led to more cubes, and more that lay back to back with each other or with the first, the one that lay open in the upper room in Nithmak. She looked out but this time did not see the room at all. Tiaan saw only stars and constellations entirely foreign to her. She tried to go further but could not get through.
She backtracked and went at what she thought was the opening again, but this time looked out on nothing but green: a dense, verdant, dripping forest. She couldn’t reach it either.