Until the day when Grandfather Peleus came to my rooms in the palace at Iolkos with the grey face of a dying man and told me I might go. He simply sent me off; he didn’t mention the message Odysseus had sent him, that the days of Achilles were numbered.

As long as I live I’ll never forget the lay the minstrel sang to Agamemnon and the Kings. Unnoticed, I stood in the doorway and drank it in, revelling in his deeds. Then the harper sang of his death, of his mother and the choice she offered him, of the fact that he considered it no choice: live long and prosper in obscurity, or die young and covered in glory. Death. That was the fate I could never associate with my father, Achilles. To me he was above death; no hand could strike him down. But Achilles was a mortal man, and Achilles died. Died before I could see him, kiss his mouth without needing to be lifted an immense distance upwards, my feet far off the ground. Men told me I had grown to almost exactly his height.

Odysseus had guessed a great deal more than anyone else, and told me as much as he knew or suspected. Then he told me of the plot, sparing no one – least of all himself – as he explained to me why my father had quarrelled with Agamemnon and withdrawn his aid. I wondered if I would have had the strength and resolution to watch my reputation marred for ever, as my father had. Heart aching, I swore Odysseus an oath of secrecy; some inner sense was saying to me that my father wanted things to remain as they were. Odysseus assumed this was an atonement for some great sin he thought he had committed.

Yet even in the decent darkness I couldn’t weep for him. My eyes were dry. Paris was dead, but if I could kill Priam for Achilles, I might be able to weep.

I dozed again. The sound of the trapdoor opening woke me. Odysseus moved like lightning, but he wasn’t quick enough. A faint, dazzling light was seeping through the hole in the floor, and legs locked together flashed against its brilliance. There were sounds of a muted scuffle, then one pair of the legs tipped over. I sensed a body hurtling earthwards; from below there came a soft thud. Someone from the horse couldn’t endure his incarceration one moment longer; when Sinon on the ground outside pulled the lever which opened the trapdoor we had no advance warning, but one of us was ready to escape.

Odysseus stood looking down, then uncoiled the rope ladder. I moved up to him. Our armour was bundled in parcels in the horse’s head, and we had a strict order of exit; as we filed to the trapdoor the first parcel a man felt was his own armour.

‘I know who fell,’ Odysseus said to me, ‘so I’ll take my armour and wait until it’s his turn, then take his. Otherwise the men after him won’t get the right bundle.’

Thus I found myself the first to tread on solid earth, save that it wasn’t solid at all. Like a man stunned by a blow, I stood on headily perfumed softness – a carpet of autumn flowers.

Once all of us were down, Odysseus and Diomedes moved to greet Sinon with hugs, kisses. Crafty Sinon, who was Odysseus’s cousin. Not having seen him before we entered the horse, I was amazed at his appearance. No wonder the Trojans fell for the tale he pitched them! Sick, miserable, bleeding, filthy. I had never seen the nastiest slave treated so abominably. Odysseus told me afterwards that Sinon had voluntarily starved himself for two moons to seem more wretched.

He was grinning hugely; I came up to them as he started to speak. ‘Priam swallowed every bit, cousin! And the Gods were on our side – the omen Zeus sent was terrific – Lakoon and both his sons perished when they stepped on a nest of vipers, imagine that! It couldn’t be better.’

‘Did they leave the Skaian Gate open?’ asked Odysseus.

‘Of course. The whole city is in a drunken sleep – they really celebrated! Once the festivities in the palace started, no one remembered the poor victim from the Greek camp, so I had no difficulty in sneaking out to the headland above Sigios and lighting a beacon for Agamemnon. My fire was answered instantly from the hills on Tenedos – he should be sailing into Sigios around about now.’

Odysseus hugged him again. ‘You did magnificently, Sinon. Rest assured, you’ll be rewarded.’

‘I know that.’ He paused, then huffed contentedly. ‘Do you know, cousin, I think I would have done it for no reward?’

Odysseus sent off fifty of us to the Skaian Gate to make sure the Trojans weren’t given an opportunity to close it before Agamemnon entered; the rest of us stood armed and ready, watching the rose and soft gold creep over the high wall around the great courtyard, breathing deeply of the morning air and inhaling the perfume of the flowers beneath our feet.

‘Who fell from the horse?’ I asked Odysseus.

‘Echion, son of Portheus,’ he said shortly, his mind clearly elsewhere. Then he growled in his throat, shifted restlessly; not like Odysseus at all. ‘Agamemnon, Agamemnon, where are you?’ he asked aloud. ‘You should be here already!’

At which moment a single horn wound soaring through the sunrise sky; Agamemnon was at the Skaian Gate, and we could move.

We split up. Odysseus, Diomedes, Menelaos, Automedon and I took a few of the others and trod as softly as we could onto the colonnade, then turned into a high, wide corridor which led to Priam’s part of the palace complex. There Odysseus, Menelaos and Diomedes left me to take a side passage through the maze towards the rooms which housed Helen and Deiphobos.

A high, lonely, drawn out scream tore the stillness apart and broke over the head of Troy. The palace passages came alive with people, men still naked from the bed, swords in hands, dazed and stupid from too much wine. Which permitted us to take our time, parry clumsy thrusts easily, chop them all down. Women howled and screeched, the marble tiles beneath our feet became slippery with blood – they didn’t have a chance. Few realised what had happened. Some were alert enough to absorb the sight of me in Achilles’s armour, and fled shrieking that Achilles led the shades of the dead on a rampage.

Murder in my heart, I spared no one. As the guards tumbled out the resistance began to harden; we had some good fighting at last, even if it wasn’t battlefield style. The women contributed to the confusion and panic, made it impossible for the Citadel’s male defenders to manoeuvre. Others from the horse followed in my wake; thirsting for Priam, I left them to butcher as they willed. Priam alone could pay for Achilles.

But they loved him, their foolish old King. Those who had woken clear-headed enough had buckled on armour and run through the warren by devious routes, intent on protecting him. A wall of armed men barred my path, their spears held like lances, their faces informing me that they’d die in Priam’s service. Automedon and some others caught up with me; I stood still for a moment, considering. The tips of their spears steady, they waited for me to move. I swung my shield round and looked over my shoulder.

‘Take them!’

I leaped forwards so quickly that the man directly facing me instinctively stepped aside, unsettling their front. The shield like a wall, I crashed broadside into them. They had no hope of withstanding such a weight of man and armour; as I fell on top of them their line broke, spears useless. I came up swinging the axe; one man lost an arm, another half his chest, a third the top of his head. It was just like cutting down thin saplings. My height and reach unmatchable at close quarters, I stood and hacked.

Bloody from head to foot, I stepped over the bodies and found myself on a pillared colonnade running all the way around a small courtyard. In its middle stood an altar raised on a tiered dais, with a big, leafy laurel tree shading its table from the sun.

Priam, King of Troy, was huddled on the top step, his white beard and hair struck silver in the filtered light, his skinny body wrapped in a linen bed robe.