The white mare stands at the centre of the stone circle. She is a pretty thing - small and neat, but she stands as if transfixed, trembling violently on the spot, standing with her slender legs splayed slightly like a newborn's. Her dark eyes are rimmed with white and her pink nostrils flare with quick, explosive breaths.

A sound to one side, and into the circle staggers a young man, obviously a hiker. The terrain is rugged and wild, and he stumbles up the slight rise of the mound and panting, regains his balance and his breath, leaning against one of the tall monoliths that form the circle. His eyes come to rest on the mare and he scowls. "Hey!" he yells, hoarsely. "Shoo! Get out of here, you! Shoo!" Seizing a handful of gravel from the ground, he hurls it at the mare.

Most of it misses, but some strikes her flanks and quarters. Clumsily flung, it cannot do more than sting slightly, but she flings her head up and whinnies piteously, scrambling clumsily to get away. The hiker seizes a pebble and throws that. It strikes her on the shoulder and the mare has had enough. With a low cry, scarcely equine at all, she wheels and flees the circle, stumbling on the loose footing and vanishing into the surrounding woodland.

The hiker sighs. He does not like horses. As a child, he and a friend once baited one in a field, and he had been terrified when the supposedly harmless animal had turned on them and charged like a bull.

He turns to admire the ancient stones that surround him. Epona's Circle, they call it, and it dates back to Celtic times. No druidic calendar this though: merely a ring of standing stones to mark a place once sacred.

He walks to the centre of the circle, standing where the mare had been. He feels a little foolish about that now - a little guilty too. He laughs nervously. Stupid to do that here, of all places. Wasn't Epona goddess of horses or some such?

As if his thoughts give life to some dormant power, the circle is suddenly different. It is not a visible change, but suddenly the man is struck by an overpowering sense of presence. The widely spaced stones now stare at him and he can feel the weight of Time contained within them. He cowers, turning slowly and lifting his arms in supplication. "I'm sorry!" he cries. "I didn't intend to hurt it! Just drive it away!"

The air in the old circle stirs and eddies; just within the circle: outside, the day is still and calm and does not admit to the possibilities within. Within, the grass begins to lean as the air circulates, as if walking around the man to observe him from all angles. It is a notion he does not enjoy: he feels like an animal at market. The sense of scrutiny intensifies until he is literally unable to move, terrified that movement - any movement - might attract more attention. He has no notion what he might have awoken, but its awesome presence fills his mind and he is overwhelmed with the immensity of it.

The air gathers speed, becoming a tightly bound cyclone with the prostrate hiker at its eye. He cringes, kneeling on all fours. "I'm sorry!" he repeats. "I'm sorry!" The air shrieks in reply. The cyclone tightens, whipping his clothes and stinging his skin with blown sand and dust. Overhead, though he does not see it, the clouds falter and reverse their course. Time is playing tricks. It is as if the circle is its own universe, obeying different laws. The wind lashes at him now. His senses are overwhelmed: he cannot see for the blasting dust: cannot hear for the howling of the wind: his nostrils and mouth are full of grit, and his whole body feels as if it is being sandblasted.

And then, between one moment and the next, everything is still, except for his pounding heart. The wind is gone. The circle is serene. He gives a ragged gasp and sags, glad he is kneeling, for he does not trust his legs to hold him. He feels like a bell or a gong recently struck. His body is still resonating, and still stunned and trembling, he waits for his body to return to his control. His senses respond, one by one. In fact they return with a dazzling clarity as if that onslaught of sensation has scoured his neural pathways and left them in the height of condition. His nostrils bring him the surprisingly sharp odour of earth and stone, and grass, as if it has just rained and released all the smells into the air. He supposes the wind had done that.

Then his stunned mind clears enough to register what all his senses are screaming at him. He is still on all fours, he knows, but he had supposed he was supported on his hands. He looks down and sees not his familiar fingers; no shirt-sleeved arm; no digital watch. He sees hooves instead, and two slender forelegs clad in a short coat of white hair. Legs, not arms. Horse, not human. And he has seen these horse legs before, though not from this vantage point. His last glimpse of them had been as they carried their owner away from his callously flung pebbles. His humanity has been stripped from him, and, he discovers with increasing horror, his manhood too. She stands as if transfixed, trembling violently on the spot, standing with her slender legs splayed slightly like a newborn's. Her dark eyes are rimmed with white and her pink nostrils flare with quick, explosive breaths.

A sound to one side, and into the circle staggers a young man, obviously a hiker. He stumbles up the slight rise of the mound and panting, regains his balance and his breath, leaning against one of the tall monoliths that form the circle. His eyes come to rest on the mare and he scowls. "Hey! Shoo! Get out of here, you! Shoo!" Seizing a handful of gravel from the ground, he hurls it at the mare.

Most of it misses, but some strikes her flanks and quarters. Clumsily flung, it only stings slightly, but she flings her head up and whinnies piteously, trying to deny what she knows will follow.

The hiker seizes a pebble and throws that. It strikes her on the shoulder and she has had enough. With a low cry, scarcely equine at all, she wheels and flees the circle, stumbling on the loose footing and vanishing into the surrounding woodland The hiker sighs. He does not like horses....