The traitor grasped the sword in both hands and raised it over his head as he came.

Perhaps the fall had hurt Llenlleawg, for even as he raised his arms, his steps faltered and his legs gave way. He crashed onto his knees and then sank onto his side as if he had been struck on the head.

Before anyone could think or move, thunder sounded over the meadow. I saw three more riders racing towards us out of the night. Like Llenlleawg, they were all in black from head to heel, cloaked, and hooded. The strangers rode to where Llenlleawg lay. The foremost sat with spear at the ready, while his two companions dismounted, pulled the stricken Llenlleawg upright, and, in one swift motion, lifted him onto the nearest horse. One of them took the saddle behind the stricken warrior, and the other gathered the dangling reins of Llenlleawg's mount and vaulted into the empty saddle. Without a word, they turned as one and rode away, fleeing back into the darkness to the taunts and cries of derision of the watching warriors.

The Dragon Flight wanted nothing more than to pursue our attackers, and we would have, too, but Myrddin, exhorting us with a bard's power of persuasion, held us in line. Stand firm in the circle of God's protection, he told us. Breaking the sacred ring now could only bring about the destruction we had so far eluded.

Oh, but it chafed me sore to see our enemies getting away, and not so much as a spear cast at their retreat.

The black riders reached the river, melting again into the deep shadows beyond the light of the burning oak. They gained the water – I heard the splash of hooves – and all at once the wood before them burst into flame.

Perhaps sparks from the burning oak, drifting across the clearing, had ignited the dry winter wood. Perhaps it had been smouldering for a time and we, preoccupied with Llenlleawg's attack, had failed to notice it. Then again, perhaps some other had set the wood to blaze. I cannot say. All I know is that even as the fleeing riders gained the water marge and splashed into the stream, a great shimmering curtain of flame arose before them. With a roar like a mighty wind, the flames struck skyward.

In a moment the fire was spreading outward on either side. The enemy warriors rode through the curtain of fire without hesitation, and disappeared on the other side.

Only then did Myrddin give us leave to break the ring. The Pendragon called us to his side and, even while praising our valour, began ordering the pursuit. While the horses were being brought from the picket, he turned to the Emrys and said, 'Myrddin, he had it – Caledvwlch! The treacherous dog raised it against me – my own sword! God in Heaven mark me, that selfsame blade will yet claim that traitor's head.'

The drought-dry wood leapt eagerly to the flame. The trail by which the enemy riders had escaped was now impassable. By the time we were mounted, the flames all but encircled the meadow, leaving only a narrow gap by which we might escape.

The Pendragon raised a final salute to the dead he left behind. Lofting his spear, he cried, 'In the name of the Lord who made me king, I will not rest until the blood debt is paid in full. Death shall be answered with death. Arthur Pendragon makes this vow.'

Myrddin, grim beside him, frowned at this, but said nothing. Many of the Cymbrogi supported the king's vow with their own. Then, turning his horse, Arthur led us away. We rode for the river and the swiftly narrowing gap of unburned wood – not in orderly columns; there was no time. Even so, before we were halfway to the water, the encircling flames closed the gap.

A quick glance behind confirmed what I already knew to be true: the forest was ablaze on every side and we were completely enclosed in a ring of fire. Smoke rolled across the meadow in billows like earthbound clouds. Gusts of heat swept over us in waves like warm currents in a freezing ocean. A sound like continuous thunder filled the night, and we urged our horses to all speed.

Arthur never hesitated, but rode straightaway into the river, where he dismounted, knelt in the water, and drenched himself all over, shouting for us to follow his example. The horses, smoke stinging their nostrils, jittered and shied, agitated at coming so near the flames.

Removing his wet cloak, the king flung it over the head of his horse to shut out sight of the flames. 'Follow me!' he called, pulling the terrified animal after him.

There was nothing for it but to stay close and follow. Flinging my sopping cloak over the head of my mount and mouthing words of encouragement to the frightened animal, I waded through the river, splashing more water over myself as I went. Arthur, having already reached the other side, paused to exhort the men to keep together, then turned and led us into the fire.

Morgaws has her captives well in hand. Arthur has joined his slattern queen; Rhys, royal bastard, shares his chains; and Merlin, vainglorious bard, now feels how tightly a true sorcerer's charms can bind. Alone among them, Gwenhwyvar might have made a useful friend. She had grit enough and guile, but Charts ruined her – turned her against me, just as she has always turned everyone against me. So Gwenhwyvar will go down like all the rest. The slut queen professes a great love for her Arthur, yet she went willingly from his bed, never once imagining that she is the one who leads him to his ruin. She thinks to save the Grail, and save her hulking husband. In truth, she only hastens his end.

They are so trusting. They actually believed they would be saved, that their god would rescue them. Perhaps they imagined the sky would open up and their miserable Jesu would float down on a cloud to bear them away to high, holy Heaven, where they would be safe forevermore.

Their disappointment, when the awful truth struck them full in the teeth, was too, too wonderful for words. Their expressions of despair will continue to delight me for ages to come. Indeed, I have so enjoyed the pursuit, it is almost a shame to see it end so soon.

But the end swiftly approaches. All that remains is to wring the last tincture of torment, fear, and pain from these, my woeful and wretched adversaries. This is soon accomplished.

Morgaws has asked to use the Grail to help bring about their destruction. A fine idea, that! We could allow them all a Last Supper, a final communion wherein the cup is passed and its contents shared among them. Oh, there are some exquisitely painful poisons where death is delayed, and the victim lingers in agony – sometimes for days.

Watching them twitch and heave in the final extremity while cursing their ineffectual god could prove highly entertaining.

I can already hear the voices of the dying as they scream out the last of their lives in utter despair. True desolation is a thing of rare beauty – the stark horror of the grave when every hope is shattered and swept away – what can match it, what can compare?

But no, I do not want them dead just yet. They have not even begun to suffer the agonies I intend for them. I mean to bring them to despair. I mean to make them curse heaven for giving them life and leaving them to their torment. I mean to harry them, removing their hopes one by one until there is nothing left but the appalling certainty of oblivion – the unendurable silence of the pit… endless… endless… endless.

Chaos reigned. All was thick smoke and fire-shattered darkness. Men shouted as they ran, stoking courage to dare the flames around them. Horses, the sting of smoke in their nostrils, screamed and thrashed, desperate to escape. We clung to the reins and pulled the terrified animals through the thick-tangled brush. The wood cracked and rang with the sound of the fire and the shouts of men, urging their mounts through the wall of fire.