As we turned the corner to the front of the main building, I discovered it was a massive two-storey villa with a central belvedere. Certainly it was not locked up! Bed linen was airing out of upper windows in the fitful sun, whilst in the dark shade between the pillars stood square plant tubs, still dripping where they had been watered shortly before. There were two immensely long wings, extending either side of a theatrical entrance; beyond this grand piece of masonry smoke wreathed, from a bath-house furnace probably. The nearer wing supported a roof garden; craning up I glimpsed fan-trained peach trees, and exotic flowers entwining the balustrade. Instead of the inward-looking design of a town house, here graceful porticos with the best view in Italy faced straight out over the Bay.

I heaved at a handle-ring in the bronze mouth of a whiskery lion's head, so my companion could push ahead through the main door. He stood in the airy atrium regaining his strength. The hall had an open roof, above a rectangular pool with a marble rim and a dancing figurine. There was an air of high tradition. To the right was the strongbox. On the left stood a small shrine to the household gods; a posy of blue and white flowers sat in front of them.

'Tell me your name!'

'Didius Falco.' Five or six slaves appeared, but hung back when they saw the two of us conversing. Suddenly certain, I smiled at the tall man. 'And you must be Caprenius Marcellus, sir!'

He was just an old crosspatch in a natural wool tunic; I could have been wrong. Since he did not deny it, I was right.

The ex-Consul was scrutinizing me down that nasal promontory. I wondered if he had heard of me; there was no way I could tell from his austere face.

'I am a private informer on an Imperial assignment-'

'That's no recommendation!' Now when he spoke I had no difficulty spotting the clean vowels and confident delivery of an educated man.

'Forgive me for barging in like this. One or two matters I need to discuss-' His resistance was growing. His slaves moved discreetly nearer; I was about to be thrown out. I waded on quickly, before Marcellus could signal them. 'If it helps,' I claimed on a lucky impulse, 'your daughter-in-law was a client of mine quite recently-'

I had heard that he was fond of Helena, but he surprised me with results: 'In that case,' the Consul answered, with a cool expression, taking back his wine flask from my hand, 'be so good as to follow me…'

Walking with less difficulty now, he stomped off past the Lararium where his chipper household deities were pointing their bronze-booted toes at the bud-vase which some reverent member of the household had placed on the shrine. Two minutes later I guessed who might have done that. We entered a side room. It had doors which stood open onto a courtyard garden where a low table was arrayed with a country lunch. I could see at least ten waiting-slaves with napkins on their arms, standing about among the potted plants. I was not invited to the cold buffet, however. The ex-Consul had a guest that day, but someone much higher class than me.

At a grey marble pedestal a young woman with her back to us was adjusting a floral display with a swift, firm touch that said when she arranged a vase of flowers, they stayed arranged. My eyes half closed as I recognized the soft curve of her neck. She heard us. I had trained my face never to show surprise, but a smile that cracked the dry skin of my lips started even before the lady turned around.

It was Helena Justina.

She was the same height as me. I could look straight into those startled cantankerous eyes without stirring a muscle. Just as well; my legs had lost all their strength.

Since I last saw her, her own clear skin had deepened its colour in the country air, while her hair developed a redder richness in which nothing so natural as country air had played any part. Today she had her hair bound up with ribbon, in a sweet, simple style that must have taken two or three maids an hour and a half and several attempts to fix. She was wearing white. Her gown looked as fresh as a great candida lily that had opened in that morning's sun, while the golden lady it was enhancing drew all my attention as the heavy lure of pollen draws a bee.

'Juno and Minerva!' she raged at the Consul. 'What's this then; your local rat-catcher-or just a passing rat?'

All the colours in the room grew brighter as she spoke.

I was really stuck now. When Helena's feelings were getting the better of her she had more light and character in her face than many women with famous looks. My heart started running at a harder pace, and showed no sign of steadying.

'This trespasser claims you will vouch for him,' Marcellus suggested, sounding as if he doubted it.

'Oh, she will, sir!'

Her dark brown eyes raked me with contempt. I grinned happily, ready to roll over at her feet like a ticklish dog pleading for more.

As a prize for a senator's daughter I was not at my best. For selling the lead with Larius I wore a workman's one-sleeved red tunic and around my waist a deeply creased dirty leather pouch where I kept Vespasian's letter to Crispus plus my lunch; today Silvia had sent us out with apples, which at groin level produced an intriguing effect. Whenever I moved a folding metal rule and set square tied on my belt clanked together stupidly. My torso was displaying broad red tracts of recent sunburn, and I could not remember when I had last had a shave.

'His name is Marcus Didius Falco.' She pronounced it like a wronged widow denouncing a thief: a widow who was well able to stand up for herself. 'He'll spin you more fables than the Sybil of Cumae; don't employ him unless you have to, and don't trust him if you do!'

No one I had ever known was so rude to me; I beamed at her helplessly, drinking it in. The Consul laughed indulgently.

Marcellus was attempting to reach a long chair, the sort used by invalids. Slaves had followed us in-ten or twelve flat-footed country cream clots, all looking so respectful it made me ill-and as he began struggling the circle tightened formation; but it was Helena who moved to him. She pulled the chair nearer, then held it firm, allowing him to sink onto it in his own time.

A man could look forward to growing old with Helena Justina in charge: plenty of scope to enjoy writing your memoirs while she made you eat sensibly and kept the household quiet for your afternoon nap… Refusing to look at me, she rescued the wine flask and carried it outside.

'Wonderful creature!' I croaked at the old man. He smiled complacently. A cheeky half-naked artisan could only admire their strong-willed lady from afar; it was understood that her life and mine would never touch.

'We think so.' He seemed pleased to hear her praised. 'I have known Helena Justina since she was a child. It was a famous day for this family when she married my son-'

Since she had divorced Pertinax, who was dead now anyway, I found difficulty answering. Fortunately she returned (all dancing crimson ribbons, and the sweet sharp spice of some highly priced fragrance from the Malabar Coast…)

'So the villain is called Falco!' the Consul declared. 'An informer-is he good at his job?'

'Very,' she said.

Then, for an instant, our eyes met.