Lines of shimmering blue appeared on the ground as if power cables were glowing just beneath the surface. They ran backwards and forwards in a grid pattern across the whole of the hill, and on the flat summit he could just make out a spike rising up to the clouds like a gigantic radio antenna.

‘Bloody hell,’ he said, awed.

‘It’s like a giant battery.’ Sophie took his hand and tugged him to the left. ‘This way.’

As they carved their way through brambles and long grass with renewed vigour, Mallory said, ‘OK, but why this place, of all the Arthurian locations?’

‘Because this is one of the most special. Legend says it’s hollow, like the one at Glastonbury Tor, which is unquestionably special. At the summer solstice, it’s supposed to turn into glass so that you can see all the secret caves inside.’

‘Aha. And it would be… what? A coincidence that we just happen to be here at the solstice?’

She smiled enigmatically.

‘And what’s supposed to be in these secret caves?’

‘According to legend, Arthur himself and all his knights, who are sleeping until England calls on their services again.’

‘More symbolism?’

She shrugged. ‘There’s more: the legend goes on to say that every seven years, on midsummer’s eve, a giant gate opens in the side of the hill allowing entry to that place.’

Mallory surveyed the imposing hill thoughtfully. ‘Looks like we’re in for a night of surprises.’

For a while, the flow of blue energy faded in and out of view, but eventually Mallory found himself picking out stronger arterial routes leading towards a focal point. As he followed the more potent lines of force, he was overcome by a strange sensation of distortion. Leaves and branches moved too quickly; shadows lengthened at an alarming rate. It felt as if time was accelerating, and when he checked the arc of blue sky visible through the foliage above them, he was unnerved to see the colour shifting to magenta as clouds hurtled overhead. The sun shifted from yellow to red and rushed towards the horizon.