‘She wasn’t talking about that Drusus,’ Tiberius retorted. ‘My son was also called Drusus!’

I swallowed hard. Of course, I’d forgotten that. On his death the rumours had come thick and fast. Many said Tiberius’s son had died of overindulgence, whilst other rumours claimed he’d been poisoned. Tiberius took a nut, crushed it in his hand, daintily picked out the fragments and ate them.

‘I have a strong hand, Parmenon. Do you know I can poke a child’s head and smash his skull?’

He didn’t wait for an answer.

‘Macro!’ He summoned the commander of the guard forward.

‘I want letters despatched to Rome. Our friend Parmenon will stay here for a few months. Well, well, we’ve got business, we’ve got business!’

I was dismissed with a flick of the fingers. My enforced sojourn at Capri had begun.

Tiberius moved as carefully as a spider weaving its web. He enjoyed the game: he sent letters to Sejanus swearing eternal friendship, and extending his condolences on the death, ‘from a fever’, of his Minion. He wrote that he wanted me to stay for a while. He even began to hint that Sejanus would be given tribune powers and be allowed to marry Tiberius’s widowed daughter-in-law, Drusus’s wife. At the same time, passage to and from the mainland was strictly controlled. For the rest I discovered how bizarre Tiberius’s existence on Capri really was. Sometimes he could be indulgent, at other times ruthless. A soldier who stole a peacock from the aviary was crucified on the cliff tops. On another occasion when Tiberius was being taken by litter from one villa to another, the bearers stumbled over a bramble bush in their path: the centurion responsible was flogged within an inch of his life.

Tiberius’s sexual exploits fascinated me. Capri was a hotbed of sexual intrigue. Macro was married to a beautiful, dark-haired girl called Aemilia. To win Caligula’s favour, Macro acted as her pimp and Aemilia was a constant visitor to Caligula’s villa. Tiberius’s practices, however, were more bizarre. All the rumours about him were true. He had his own private bawdy house where sexual extravangazas were staged for his secret pleasure. Young men and women from all parts of the Empire, adept in unusual sexual practices, would be encouraged to congregate before him in groups of three or four to excite his flagging passion. This bawdy house consisted of a number of rooms decorated with the most obscene pictures and statues available. It even boasted a small library with erotic manuals from Egypt so these sexual athletes could learn exactly what was expected of them.

Macro led me on a tour of all this, like a Roman taking a provincial visitor round the city. The rooms were opulently decorated, drenched in perfume, furnished with couches and stools for the Emperor and his coterie of favourites. Spy-holes had been drilled in the walls, floor and ceiling. The ‘Sexual Athletes’, as Macro called them, were confined to their own private apartments. They wined and dined on the most exquisite aphrodisiacs and were under strict orders to save their energies for the Emperor alone. Macro also took me into the woods. Special glades had been set aside where boys and girls, dressed as Pans and nymphs, prostituted themselves in caves or grottoes. No wonder the wits had re-named Capri ‘the Place of the Goat.’ Macro hinted at other obscenities.

After from my initial interview with the Emperor I became, to all intents and purposes, Macro’s creature. On one occasion he asked about Agrippina. Was she well? How did she look? Her husband Domitius? Had she taken new lovers? I was pleased I could tell the truth: I knew nothing.

‘What will happen?’ I asked, trying to change the topic of conversation.

‘Be careful,’ Macro warned. ‘Tiberius can be excitable and as changeable as the moon. Letters have been despatched to Rome with conflicting messages. Sejanus doesn’t know whether he’s on his head or his arse, if he’s still the Emperor’s favourite or not.’

Macro scratched the tip of his nose.

‘Tiberius could play this game for months, even years. He might forget it or change his mind.’

‘And me?’ I asked.

‘Are you so desperate to get back to Agrippina?’ Macro sneered. ‘Quite a little courtesan, isn’t she? Her brain teems like a snake pit. You should be careful, Parmenon. Tiberius might decide he can’t do without Sejanus.’

‘And Caligula?’ I asked.

Macro breathed in.

‘According to all the rules, Gaius Caligula should be dead. To understand Caligula you have to understand Tiberius’s mind. I can speak to you bluntly, Parmenon, because no one would believe you if you were to repeat what I say. Tiberius is nourishing Caligula as he would a viper; that young man is to be Tiberius’s revenge on Rome.’

‘And yet you support him?’ I bit my lip immediately.

‘Do I?’ Macro taunted, drawing his brows together. ‘I support no one, Parmenon, except the Emperor. You are new to this game, aren’t you?’ He drew closer. ‘Remember the first and only rule: keep your mouth shut!’

I soon grew tired of Capri and I missed Agrippina. I would have loved to have sent a message but that would have been dangerous, even foolish.

At the beginning of October I was still wondering how I could arrange my departure from Capri when Macro aroused me before dawn on one cold, dark morning.

‘Get dressed!’ he urged. ‘Quickly, we are for Rome!’

Two biremes stood ready in the harbour; one full of marines dressed in half-armour, a savage-looking bunch totally under Macro’s command; the second bireme contained members of Tiberius’s own personal guard. We clambered aboard and within the hour were heading for a pre-arranged spot somewhere to the south of Rome. No imperial colours were shown and Macro took advantage of the sea mist, as well as the early hour, to keep well clear of the normal shipping lanes. The pilot guided us in, and both biremes beached in a sandy cove some miles south of Ostia. We came ashore like an invasion force: scouts were sent out; fires were lit and breakfast cooked; sentries were deployed. We spent the rest of the day bringing supplies ashore whilst spies crept in from Rome. The news they brought was favourable, the Senate was to meet the following morning.

Once darkness fell Macro marched his troops along the coastline. It was still dark when we reached the Viminial Gate, where Macro displayed the imperial passes and we were allowed entry. How strange to be back in Rome! I was desperate to see Agrippina but Macro’s orders were strict: the will of the Emperor was to be carried out and I was Macro’s accomplice. The marines and bodyguard marched to the Palatine where Macro concealed them in a small park. He took off his own armour and, in the torchlight, washed and shaved and put on clothes appropriate for a visitor to the Senate. We went up the Palatine, into the exquisitely beautiful heart of Rome with its fluted columns and finely carved statues. The great temple of Apollo, built of gleaming Parian marble, its vast doors inlaid with ivory, dominated this lavish concourse. The Senate was scheduled to meet that morning.

I felt giddy, slightly nervous. It was such a bewildering contrast to the solitude of Capri with its tangled woods, sinister secrets and silent villas. Dawn broke. Macro, easily hiding his tension, sat on a marble bench at the top of the steps leading into the temple; whilst the officers of the marine guard and I stood behind him. The sky turned a blue-pink as the sun began to rise. The braying of horns and conch blasts shattered the silence as the city came to life. Senators appeared, dressed in their white togas, with scribes and house retainers behind, carrying parchment and leather bags. They all stared nervously at Macro who nodded but sat impassive.

Sejanus, of course, had heard the news of our arrival and came hurrying up with his entourage. No longer so calm and self-possessed, he looked red-eyed and wary. Macro rose to meet him, but Sejanus waited at the foot of the steps until his Praetorians deployed around him in a semi-circle: a grim threatening ring of steel. The soldiers were dressed in their red and leather kilts, greaves, boots, embossed breast-plates, and plumed helmets. Each carried an oblong shield, and all had their swords drawn.