‘Go, tell Sejanus’s minions,’ she whispered, ‘that I am of the blood imperial. I have been attacked! A lowling has tried to rape me. I demand to see the Emperor!’ She grabbed my hand and pulled me closer. ‘Use your wit, Parmenon. Act as if you were truly Sejanus’s spy. Tell the truth!’

I left immediately, threading my way through the passageways of the Palatine Palace across the parklands. Darkness was falling, and torches and lamps were being lit. I found the Minion in the same chamber in which we had first met. I suspect he already knew what had happened but when I gave him the details his face paled. He plucked at his face and sifted the parchments on the table.

‘I see. I see,’ he muttered. ‘You’d best stay here.’

An hour passed. The darkness deepened, the light from the oil lamps gutted out. At last the Minion returned.

‘His Excellency will see you now!’

‘So, she wishes to go to Capri?’

Sejanus lounged on a couch, one arm on the headrest, a wax writing tablet on his knee. A small tripod next to the couch held quills, ink and pumice stone. He put the tablet down and glanced at me, fingers laced. Sejanus was at his most avuncular: patrician, his grey hair carefully combed, smiling eyes, slightly hooked nose, his face freshly shaved and oiled.

‘I’ve heard what happened.’ He smiled. ‘Do you believe it?’

I recalled Agrippina’s advice.

‘No, I don’t, Excellency.’

Sejanus furrowed his brow. ‘I am glad you said that. Neither do I. Metellus was a cold fish, who prefered little boys to women so why should he try and rape Agrippina?’ He clicked his tongue.

I was standing about three yards from him. I hoped he couldn’t smell my fear.

‘But Agrippina acted foolishly. Surely she would have known about Metellus’s preferences? Let me think this through.’ Sejanus reflected. ‘Agrippina sent you to bring Metellus to her room, and then locked the door. Almost immediately she started to scream a yell and when the Praetorians broke in, Metellus, one of my spies, was found with a dagger thrust through the heart. Now Agrippina is acting the hysterical bitch and pleading to be sent to Capri to complain to the Emperor.’ He sighed. ‘To be perfectly honest I suspect the Divine One won’t believe her either.’

He lowered his head and clicked his tongue. I stared round the marble room. Purple and gold drapes hung against the walls and two crumbling gravestones, a memento mori, perched at either end of the couch. Was it Sejanus’s idea to terrify visitors or had this been the great Augustus’s writing chamber? The furniture was exquisite, much of it of Egyptian design, as were the statuettes — an Apis bull, a Hermes, a dancing girl — and a silver lamp-stand carved in the shape of a tree. Agrippina later explained that it was all looted from Cleopatra’s court. At the time I didn’t really care, only aware of the warmth and the brooding silence. The drapes moved slightly, and I glanced down and caught sight of the toe of a boot peeping out beneath. Sejanus was no fool: he appeared to be frightened of no one but the chamber was full of guards, their swords drawn, ready to protect him or to carry out his slightest whim. He continued to click his tongue, an unnerving sound: sometimes fast, sometimes slow it seemed to echo the beat of my heart. I stared down at the floor and studied the mosaic which was of Demeter rising from the corn fields.

‘I am wondering,’ Sejanus smiled, ‘dearest kinsman, if you are part of this plot?’

He picked up a bell and rang it vigorously. A door in the wall opened and the Minion stepped through. Sejanus didn’t even bother to turn his head.

‘Who’s in the chamber below?’ he demanded.

‘Tibullus.’

‘Ah yes, our self-styled poet who thinks he is a new Virgil. Any progress?’

The Minion shook his sweat-soaked face.

‘Take my kinsman Parmenon down.’

The Minion snapped his fingers, and I followed him out. The chamber beyond was pitch black except for a torch flickering at the bottom of the steep, sharp steps. The Minion grabbed me by the arm and bustled me down.

‘Don’t be frightened!’ he sniggered.

I wished I’d fled. Agrippina’s plot was doomed to failure. Sejanus had realised what she was up to. She wouldn’t be travelling to Capri and I was about to end my days in a place like this. We reached the bottom of the steps and went along a poorly lit corridor which debouched into a circular chamber, where I saw men dressed like gladiators and satyrs, the masks over their faces made all the more grotesque by the leaping torchlight. The smell was as fetid as that from an open latrine. The grotesques moved away to reveal the outstretched body of a man on the table.

‘He’s not a prisoner,’ the Minion sniggered, pointing at me. ‘At least not yet. Just show him.’

One of the grotesques pushed me forward. Tibullus, or what was left of him, lay outstretched on a table. He was completely naked. He had lost consciousness but the vinegar-soaked gag in his mouth would have blocked his screams. Blood soaked both him and the table, oozing from small puncture holes in his body. I froze in horror. The table top beneath was covered in a forest of small spikes. Tibullis was literally being tortured to death by a thousand cuts. Each time his body was moved and turned, the nails either dug afresh or cut deeper into the open wounds.

‘He wrote a poem, Tibullis did,’ the Minion explained. ‘What we are trying to discover is who paid him?’

‘I didn’t!’ I snapped, trying to hide my fear.

‘No, of course you didn’t. But you get the message?’

‘Very clearly.’

‘Good, good.’ The Minion put a scented pomander to his nose. ‘Do remember what you’ve seen.’

I stared at the torturers, at their sweat-soaked, balding pates, eyes glittering behind the masks. They were full of a malicious enjoyment at the sight of another human being torn to pieces. I followed the Minion up the steps back into Sejanus’s chamber.

‘Is Tibullus still alive?’

‘Yes, Excellency.’

‘Well, he won’t be by tomorrow morning. Right, Parmenon, were you party to this nonsense with Domina Agrippina?’

‘To some extent,’ I replied.

Sejanus glanced expectantly at me. ‘You need to do better than that, kinsman!’

‘Domina Agrippina was hysterical,’ I lied. ‘She recognised who I really was as soon as she met me at the Games. “I am your secretarius,” I announced. “No,” she hissed. “You are a spy!” She returned to the palace, where she started to make extravagant promises about what she could do for me.’

‘And?’

‘Excellency, I pretended to listen to her, until she told me to get out. Metellus went in to see her.’ I shrugged. ‘The rest you know.’

‘And would you send her to Capri?’ Sejanus asked.

I stared across at the secret door, which the Minion had closed. I took a step forward and one of the drapes moved.

‘No, Excellency, I wouldn’t risk it. Only the Gods know what kind of mischief she could get up to.’

Again the clicking tongue. I was in a cold sweat: the next few seconds would decide my life.

‘So, what do you advise, kinsman?’

‘According to public report,’ I blurted out, ‘a woman of the imperial family was attacked, the daughter of Germanicus. I saw the outrage on the soldiers’ faces: Agrippina’s story will be believed.’

Sejanus, cupping his chin in his hand, nodded.

‘If you do send her to Capri,’ I continued, ‘it could be dangerous. But if you refuse, you can be sure that some spy will carry the story to Capri and the Emperor might think someone is trying to hide something.’

‘Very good! Very good!’ Sejanus smiled. ‘Kinsman, pour yourself a goblet of wine.’