‘I don’t know, but I mean to ask Rheagor,’ I said determinedly, noticing that there were wisps of steam above the surface of the water which the light had transformed into golden scarves. I was still mustering my arguments for Rheagor when we dismounted, but the pack leader was already padding towards me.

‘This be the graag that I did see seliga and which this one’s ancestor – the first Brildane – spoke about,’ the wolf announced. ‘The graag goes under the shining earth. There be no taint in it and no taint can pass through its walls.’

The graag was the pipe and we were to go through it, I thought, feeling almost light-headed with relief. I had thought the wolf had meant the glowing wastelands when he talked of the graag! The pipe was easily large enough to clear a horse without its rider, though it might be difficult to get the horses and wolves up into it, depending on the depth of the pool. It would take us days if we had to build some sort of ramp.

‘Was the water hot when your ancestor came through the graag?’ I asked.

‘It did be hot but not scalding as the pool in the valley of the Brildane in the mountains,’ Rheagor answered.

I went to the edge of the water and knelt, seeing without surprise that there were radiant clusters of Jak’s taint-devouring creatures around the edges of the pool. It looked deep, but it was not tainted. The green of the glowing earth in the distance had made the water in the cut look greenish. In truth the colour it gave off was as fresh butter or new-minted gold coins.

I held out my hand palm down just above the surface of the pool and felt only a pleasant dampish heat. Even so it was with some trepidation that I dipped a finger into it. As Rheagor had said, the water was not boiling. I turned to look at him and only now noticed that he had wept a dark half-moon of tears into the fur beneath each slitted eye. The brightness hurt his eyes. That was why the other wolves were standing back from the water.

‘They do keep watch as well as shield their eyes,’ Rheagor sent. I frowned and strengthened my mind shield, not liking the way he had plucked my speculation from my mind.

‘Does the graag stay level in the ground?’ I asked, thinking of the horses. I knew well how deeply the Beforetimers had penetrated the earth in their passion for building and burrowing and there was no question that the pipe was a Beforetime construction, though I could not imagine what its purpose had been.

‘This one’s ancestor did tell that the graag did go shallow under the earth,’ Rheagor said.

‘How long is it?’ I asked, thinking I might as well take advantage of his sudden willingness to answer questions.

‘The journey do take two days and one night for stopping.’