‘Your escort is waiting. Give this to my brother Gaius and no other. Tell him his sister loves him.’ She moved so her back was to the rest of the room. ‘Tell him,’ she continued slowly, ‘to play the man and act the part. Remind him of the herbarium I sent him. He is to study it closely for the source of his deliverance is in Capri.’

She turned as if to walk away but came back.

‘Oh, and tell the Emperor that Sejanus wants to become Drusus: that’s why Drusus has gone away.’

I stared perplexed. Drusus, her brother, was in a dark hole beneath the Palatine. She blew me a kiss and walked over to one of the servant girls, shouting for water and napkins and the clearest mirror they could find. I went down to the yard. The Minion was waiting, with a small cohort of troops and one of those huge four-wheeled carts to carry our baggage and other supplies for the Emperor in Capri.

‘You are ready, kinsman?’ the Minion mocked.

He looked me over from head to toe. I was dressed in a dark-green tunic and a rather threadbare cloak I had bought in the market place. He threw me a clinking purse.

‘When you return to Rome you really must visit my tailor.’

I caught the clinking bag, and saw that his hand was still outstretched. I gave him Agrippina’s letter, he broke the seal and studied it carefully.

‘Nothing treasonable,’ he sighed. ‘More’s the pity. Here!’ He tossed it to a servant. ‘Take that to His Excellency!’ He gestured at me. ‘Come on! Ostia awaits!’

I was given a sorry nag to ride. We left the Palatine by side gates and made our way through the narrow, stinking streets towards the gate to Ostia. It was late March. The sun was beginning to strengthen but really the seasons made little difference in Rome. It was always busy with merchants’ carts, pedlars’ barrows, the cookshops and wine stalls, the jostle and bustle of an empire. Soldiers forced their way through the crowds. Sailors and marines, up from the docks, searched out the ladies of the town. Fruit and vegetable-sellers shouted and sold their produce whilst trying to evade the market police. Astrologists, soothsayers, magicians and conjuring men clustered about. I heard at least thirty different tongues being spoken. I wondered if it was the last time I’d see this city. Some wit cracked a joke about the nag I was riding but I ignored him. We were soon through the city gates, onto the broad road to Ostia.

A trireme was waiting at a well-guarded quayside, Tiberius’s personal craft. It was a grim-looking vessel, it flew the imperial colours, but its sails were black and white, and the marines and officers on board were all dressed in dark leather corselets or tunics. It was the quietest ship I have ever sailed on and provided an insight into Tiberius’s suspicious mind. No one trusted anyone and the best way to keep your head was to have a quiet tongue. We were welcomed gruffly aboard, and our baggage was stowed away. Orders rattled out and we were soon leaving the quayside, as the trireme’s prow, curved in the shape of an eagle, sliced through the water. The fishing smacks and pedlars’ boats kept well away from our vessel, recognising the colours: the red and gold prow, the silver gilt along the rail and the dark sails.

The sea was calm, the winds favourable, the journey short; I was pleased to see the Minion was as seasick as I. At last Capri came into sight. Tiberius had chosen the island well. It was only a short distance from Rome, but well protected by its soaring cliffs which allowed only one natural harbour. Even as the trireme skimmed towards this, I glimpsed the armed men on the cliff tops. The Minion whispered to me that the Emperor had constant lookouts posted there with beacons at the ready, vigilant for the hint of any danger, any threat to the Emperor. Tiberius truly hated Rome. He viewed it as a place full of devils and went there as little as possible. He had even failed to return for his own mother’s funeral: her corpse had begun to decompose before Tiberius allowed the funeral rites to take place. Sometimes he travelled to outskirts of Rome, issuing orders, receiving envoys and quickly departing.

Tiberius also hated religion. He had no time for the Roman Gods or any others and neglected the temple ceremonies. He was, however, deeply interested in the science of the Chaldeans: the soothsayers, diviners and oracle-tellers who might predict the future. The most famous, Thrasyllus, had once promised that Tiberius would be Emperor. Consequently, Tiberius took such men and women seriously. But woe betide any whom Tiberius considered charlatans. They were invited to Capri and, once they had completed their business, were taken down the steps along the cliff edge. If Tiberius was unhappy with his soothsaying guest, a burly guard had secret orders to tip him onto the rocks below. A sinister, ominous place!

The trireme soon docked, and ran down its gang-plank. I had been in many harbours and ports throughout the Roman world, but found Capri was the quietest. Everything was closely regulated, and there were none of the usual swaggering sailors or tempting courtesans. We were welcomed by the commander of the Emperor’s bodyguard, a stocky, thickset man, dressed in full armour. At first I thought he was the usual dim-witted bully boy until he clasped my hand, and I saw that the eyes beneath his heavy brows were bright and cynical. He looked me over from head to toe.

‘Another of Sejanus’s creatures,’ he murmured. ‘I am Macro.’ and withdrew his hand. He nodded at the Minion and ordered us to follow him.

Capri had been taken over completely by the Emperor. Macro explained, as we followed the path up to the cliff top, that there were twelve villas in all for the Emperor, his guests and household. Gardens and temples had also been laid out and built. We were given apartments in a villa not far from the harbour. Macro informed us we had an hour to make ourselves ready before the Emperor would see us.

‘So soon?’ I asked once Macro had left.

‘Tiberius doesn’t like visitors,’ the Minion replied. ‘Though he’ll be eager for news from Rome.’

‘I thought. .’

‘What?’ the Minion demanded.

‘Macro already seemed to know that I would be I coming here?’

The Minion gave a shrug. ‘You have your orders. Make sure you follow them.’

We washed and changed, then ate some white bread and grapes. Macro returned and we were led across the island to a white, marble-colonnaded villa perched high on the edge of the cliffs. It was cooled by breezes which also wafted in the perfume of exotic plants from the garden.

Tiberius met us alone in a small atrium which overlooked the garden. I glimpsed a sparkling fountain and the curtain wall, beyond which was the death-dealing fall. Tiberius sat between two pillars leading out to the garden. He didn’t recline on a couch but on a soldier’s camp chair. He was dressed in a purple and gold-fringed toga, with a simple bronze chain around his neck. He kept playing with the silver tassels on the cushions beneath him. Despite Sejanus’s warnings, I glanced up at him quickly. Tiberius looked hideous: although balding at the front, his dark hair clustered thickly round the nape of his neck, his nose was twisted slightly to the left, the jutting upper lip was made worse by the rotting teeth, and a weak chin gave his face a bitter, sneering look. His glowering dark eyes blazed in contrast to his skin which was a dirty-white like that of a whore who’d painted her face, emphasized by the fetid ulcers which covered his body. Years earlier Tiberius had tried to burn these off by cauterising them with a fiery iron. Such a clumsy cure had only made matters worse. Tiberius reminded me of a leper.

We had to wait until Macro finished his whispering. Tiberius pushed him away and beckoned us forward with his fingers. We knelt on cushions before him, heads down.

‘You come from Rome?’