We had eaten and cleaned up when sunlight suddenly shafted brilliantly down through a widening gap that had opened up in the darkening clouds which all but covered the sky. I had not realised until then how dark it had become. We all lolled by the fire for a time in companionable silence, enjoying the sun, then Analivia offered to read some more of Jacob’s journal to the others. I left them to it and went up to the weeping archway to fill the water bottles. It was a tedious business because, although the ground about the arch was sodden, the water did not pool anywhere, so I had to catch it falling. I was halfway through the gourd bottles when I heard a shout and turned to see Swallow beckoning urgently. Wondering if they had found something in the journal, I stoppered the bottle I had been filling, gathered the rest, filled and unfilled, and hurried to the hollow.

‘What is it?’ I asked, as Swallow took the bottles from me and handed them to an excited-looking Analivia.

‘I’ll show you,’ he said, and he took my hand and led me firmly to the furthermost northern edge of the plateau. Instead of looking down, Swallow took my shoulders and turned me directly east to face the mountains behind the plateau. Then he pointed to the narrow gap between them.

I gaped, for from this angle I could see that there was a stone bluff jutting out into the gap about halfway up the southern peak. Atop it was a building, the likes of which I had never seen before. It was too high for me to be able to make out much detail, but it had a round roof split through as if some giant with a sharp knife had cut a thin slice through the centre of a pie. The building was so white as to have been made from a block of snow, and with the sun shining directly on it and the dark stormy sky beyond the gap, it shone like a beacon.

‘It is the building Jacob scribed about,’ Analivia said eagerly, having come with the others to join us. ‘The Taillard Observatory. He said he needed to go there to see the dream city. It can’t be an accident that we have stumbled upon it!’

‘I am inclined to agree,’ I said, studying the face of the mountain under the bluff. There was a talus that would be easy enough to surmount, but the rest of the climb would be virtually straight up, unless we could go around the talus to find some easier ascent. I could see now why the Beforetimers had created such a gateway and smoothed the plateau. It was the way to the mysterious Observatory. But what was observed from it, other than mountains, and how had the Beforetimers climbed up to it?

‘I told you she would want to see it!’ Analivia said triumphantly to Swallow.