They went to the edge of the pool, where it trickled over the side of the little hillock and down among the field of boulders. Isaac reached down to a spot where it flowed between two of the enormous rocks and dipped his fingertips in the water. Patterns of frost spread out instantly, like blossoming flowers, and in a few seconds milky-white ice began to form.

For a while Alice worried that Isaac had been right. The boulders were too heavy, or too close together, or else the iceling simply wasn’t strong enough, whatever Isaac claimed. Then, with a faint groan, the huge boulder shifted, just a fraction of an inch, as the expanding ice forced it upwards. Tons of rock shivered, letting fall a rain of dust and pebbles. It moved a little further, perhaps an inch, and Isaac pulled his hand away. Instead of lying directly against the neighbouring boulder, the rock was now resting on an inch-thick layer of dirty ice.

‘I didn’t know it could do that,’ Isaac said.

‘At home,’ Alice said, ‘we once had a hard freeze right after a rain. Some of the piping on the roof burst. Father brought it down to show me afterwards. Solid iron, but the ice broke right through it. It expands when it freezes, you see, and . . .’ She shook her head, not wanting to think about her father. ‘All right. It works. Now, let’s get ready before that thing comes looking for us.’

Chapter Twenty-seven: The Trap

CHAPTER TWENTY-SEVEN

THE TRAP

The strain was evident on Isaac’s face by the time they were done. He had the look of a man struggling under some enormous weight, brow furrowed, teeth clenched, hard-pressed but determined not to let it fall.

‘Are you all right?’ Alice said.

‘I can hold it,’ Isaac said. ‘For a while, anyway.’

‘If it gets away from you,’ Alice said, ‘for God’s sake say something. I’d rather not end up buried under a thousand tons of rock.’

‘I’ll hold it.’ He puffed a breath between his teeth. ‘I’m more worried about you. Will you have time to get away?’

‘I think so.’ Alice thought about the huge eye trying to focus on her. ‘I don’t think it’s very good at going from light to dark and back again. I should have a few seconds before it can even see me.’

‘That’s a thin guess to bet your life on.’

‘If you had any better ideas, you should have said so earlier.’

Isaac shook his head. They stood in silence for a moment.

‘Well,’ Alice said. ‘Let’s get started.’