Caesar began to climb the staircase, leaving Antonius and Brutus behind, deep in conversation. Realisation struck Romulus like a blow from Vulcan's hammer. It was all part of the plan. The conspirators only wanted to kill Caesar, so they would delay his greatest supporter outside. Romulus wanted to scream out loud. Could no one else see it? Stay calm, he thought. All was not lost – yet. How would they kill Caesar? Togas were not the kind of garment that facilitated the concealment of weapons. Was there a secret stash inside? He discounted that theory at once. Too many other people – priests, acolytes and devotees – had access to the temple.

Then Romulus' eyes were drawn to the stylus cases in each senator's hand, and his stomach lurched. The elegant wooden boxes were just the right size to hold a knife. His mind reeled at the simplicity, and the lethality, of it. Despairing, Romulus' gaze drifted up from the ascending group. There, across the width of the steps, at his level he saw Fabiola. They locked eyes, staring at each other with an unbearable intensity. After a moment that seemed to last for ever but in reality was probably no more than several heartbeats, Fabiola's mouth opened.

Before she could speak, though, Caesar had reached them. Surrounded by the mass of senators, he was talking about Longinus' son's great day. Assuming the toga of a man was one of life's most important events. Antonius was still at the bottom of the steps talking to Decimus Brutus. Romulus felt more weary than he had in his life. He was just a helpless observer.

'I am here,' said Tarquinius from behind him.

Romulus could have almost cried with relief. 'Will you come with me?'

'Of course. That's what comrades are for,' the haruspex replied, unslinging his double-headed battleaxe.

'We might be killed,' said Romulus, eyeing the six guards, all of whose attention was on Caesar.

'How many times have I heard that?' Tarquinius smiled. 'Still doesn't mean I can leave you to go in alone.'

Romulus turned away from the crowd and drew his gladius. He shot a glance at Fabiola, but she was too busy watching the dictator. A mixture of emotions twisted her beautiful face, and Romulus thought of their mother. What if his twin was correct? he asked himself again, despairingly. His gut instinct answered at once. Even if she was, Caesar did not deserve to be killed like a sheep surrounded by a pack of starving wolves. So he wasn't going to back away now.

Romulus watched tensely as the dictator passed out of view. To his delight, four of the guards also entered, leaving only two at the doors, which remained open.

Now it was down to Mattius.

He took a couple of steps towards the entrance, and Tarquinius followed suit. Talking to each other, with half an eye on the proceedings within, neither guard noticed for a moment. Romulus slid his caligae across the stone, getting a few paces nearer.

'Romulus!'

Fabiola's shout was like the crack of a whip in a confined space.

Romulus stared at her, aware that the guards had seen him.

'What are you going to do?' she screamed.

An image of Velvinna's suffering burned every part of Romulus' mind. It was followed by one of Caesar smiling as he granted him his manumission in the arena not three hundred paces away. Torn, he glanced at Tarquinius.

'Your path is your own,' whispered the haruspex. 'Only you can decide it.'

'You two!' yelled one of the guards. 'Drop your weapons!' Calling for help, he and his comrade advanced with lowered pila.

They were stopped by an animal cry of pain from inside the temple.

'Casca, you idiot, what are you doing?' Caesar demanded.

'Help me,' shouted a voice. 'Kill the tyrant!'

'Romulus!' screamed Mattius. 'Come quickly!'

A baying sound of anger rose and Romulus heard the muffled sound of blows landing. Fury consumed him. Raising his gladius, he leapt forward at the two guards.

The gods were smiling down at that moment. Distracted by the commotion inside, both their heads were half turned away. Romulus was grateful for this – he had no desire to hurt them unnecessarily. Reversing his gladius, he brought down the hilt hard on the back of the nearest man's skull. From the corner of his eye, he saw Tarquinius using the metal-tipped butt of his axe to do the same with the other sentry. Jumping over the falling men, they sprinted inside.

Fortunately, the remaining guards had been totally distracted by what was going on, so their path was clear. Romulus' eyes opened wide at the splendour of the long, high-roofed chamber, which was well lit thanks to the number of small glass-paned windows high on the walls. Of course his attention did not remain on the decor, or the ranks of toga-clad senators who were on their feet, shouting and pointing. Clearly most of the six hundred had known nothing about the attempted assassination. Romulus felt disgust that none had tried to intervene. On he ran, to the central area where the consuls' chairs and that of Caesar stood. He could make out a cluster of men there. All were carrying knives, and many already had bloody robes. Their faces had the empty, shocked look of those who have just grasped the enormity of what they've done.

I'm too late, Romulus thought, anguish tearing at him like the claws of a ravening beast. As I thought I would be. Screaming his fiercest battle cry, he charged straight at the assassins. Tarquinius loped alongside, lean and grey-haired but terrifying-looking with his raised axe. Romulus was dimly aware of Mattius pelting along to his rear, adding his childish voice to the clamour. To his surprise, their cries had the most dramatic effect. Scattering like a flock of birds attacked by a cat, the assassins broke and ran, stampeding up into the tiers of seating. Their fear was infectious, and within a few heartbeats, the entire body of senators was fleeing along the sides of the chamber and out of the doors. Their departure revealed the most bloody of scenes.

Beneath a large statue of Pompey, Caesar lay in an expanding pool of his own blood. His entire toga was covered in damning red stains, each one the mark of a knife's entry point. His chest, belly, groin and legs had all been wounded. The white woollen garment had been ripped off his left shoulder, and there too Romulus could see multiple stab and slash marks. Caesar resembled a badly butchered side of pork. No one could survive that many injuries. Skidding to a halt, Romulus dropped to his knees by the dictator's side. His eyelids were closed. Shallow, shuddering breaths shook his chest and his skin had already assumed the grey pallor of those near death.

'What have they done?' Romulus wailed. An all-consuming grief flooded him that Caesar's life should end like this.

Shocked by the bloodshed, Mattius hung back.

'Romulus?'

Startled, he looked down at Caesar, whose eyes had opened. 'Sir?'

'It is you…' Caesar's breath rattled in his chest.

Romulus found himself clutching one of the dictator's bloody hands. 'Don't say anything, sir,' he said frantically. 'We'll soon get a surgeon to fix you up.'

Caesar's lips turned upwards. 'You're a poor liar, legionary,' he whispered. 'I should have listened to you about coming here.'

Romulus hung his head, trying to hide his tears. All his efforts had been in vain. A moment later, he felt his hand being squeezed.

'You're a fine soldier, Romulus,' Caesar gasped. 'Remind me… of myself when I was younger.'

Romulus' instant feeling of pride at this enormous compliment lasted no longer than two heartbeats. Beads of clammy sweat broke out on his forehead, and he pulled away his hand. Raging doubt filled his mind.

Caesar looked confused. Trying to sit up, he started off a fresh bout of bleeding from his wounds. It was too much for him, and he sagged back on to the marble floor. His eyes took on the distant stare of those who can see Elysium, or Hades.