O great computer! (Mercury)

Over the next few weeks he perfected the plan. There could be no risk of being seen, he realised: neither the local police nor the curators would welcome any further intransigence on his part. He made fewer observations—he could conjure the stones both seen and unseen at will, which was more than the site itself could provide him with—and no experiments at all, so as not to raise suspicion.

One day, he knew, he would have to make it his last ever journey to the stones. The house move was in a week's time, and most of his parents' belongings were already packed. They hadn't been into his room yet, but he knew they would venture in there soon enough, with unflattened boxes, suitcases and tea-chests. He couldn't risk them finding his maps, even though they might not themselves lead to his secret. Besides, it would be a suitable day to bid his farewells, he decided: there was a planetary conjunction, and it was a perfect division of the times between both solar and lunar eclipses.

Satisfied with the astronomical fitness of it all, he methodically tore his great drawings into strips, and the strips into rough squares. These he soaked to a pulp in the sink, and then ran the waste disposal unit. The flattened marbles he put in his pockets: he could drop those into the bins in the centre of the town. When there was nothing left except in his mind's eye, he left the house. At the end of the road he turned to look at his home in the distance, and murmured: "Bye." Then he turned the corner and made towards the henge.

There were no mistakes: every step he trod across the site was accurate to the millimetre, so much so that he was sure he could sometimes see the outlines of the lines in his mind glowing in the grass under him. And they never saw him, any of them: not the tourists, the guides, the security guards or the curators; not even his parents, or his Auntie Jean's family; nor could the police find him, though eventually they came looking mob-handed, with most of Larkhill and a handful of journalists in tow. The local police were hardly the acid test for discovery, but if the paparazzi could not track him down, nobody could.

And though there has been talk ever since, of a young man who haunts the stones; whom visitors sometimes swear they have seen out of the very narrowest corners of their eyes; whom the occasional nightwatchman might claim to have spied crossing the site at night, and followed to a sarsen only to have the figure before them vanish as if he had never been there; it was only talk, and nobody was ever to lay solid hand or convincing eye on the fleeting figure. Finally, for Rhys, everyone had gone away for good.