Don't drink and delve. Hot toddy after a long walk goes straight to the bladder, for one thing. You'll never persuade the guild treasurer to admit he defrauded the funeral club so he could take three girlfriends to Lake Trasimene, if you are absolutely bursting to relieve yourself. Quadrumatus Labeo lived outside the city on the old Via Aurelia. I trotted out of Rome through the Aurelian Gate, and kept going until I found a finger post with red letters announcing that the right estate lay up the next carriage drive. It took less than an hour, even in the dead of winter when days are short so the hours into which they are divided are also at their shortest.

I supposed his home's location was what had made Quadrumatus attractive as a potential host for Veleda. He had an isolated villa on the western side of Rome, so she could be brought up from Ostia and slid into the house without passing through any city gates and without too much attention from nosy neighbours and tradesmen.

There was one significant disadvantage. The priestess was the responsibility of the Praetorian Guard. I considered it critical that the Praetorian Camp lay outside the city too – but on the eastern side. The captive and her minders were thus separated by a three-hour walk across the whole of Rome, or four hours if you stopped for refreshments. Which, in my opinion, you would have to do.

That said, there was not much wrong with the place. Since Quadrumatus was a senator, he had a decent boundary thicket to stop sightseers watching his summer picnics in the grounds. These grounds were stuffed with shady stone pines and much more exotic specimens, jasmine and roses, topiary that must have been maturing since the time of his grandfather the consul, dramatic long canals, miles of triple box hedges, and enough statues to fill several art galleries. Even in December, the gardens were awash with groundsmen, so intruders looking for a priestess to snatch would be spotted long before they reached the house. If intruders came on foot, they would be weary anyway. I was, and my home was well placed for this adventure. I had only had to stroll along the Aventine embankment gazing at the muddy, swollen Tiber, nip across the Probus Bridge and head out through the Fourteenth District, the Transtiberina, which is the roughest part of Rome so you don't linger. I had passed the Naumachia on my left, the imperial arena for mock sea battles, then the Baths of Ampelidis on the right, and met the old Via Aurelia which travels into Rome by a shorter route than I had come on, passes the station house of the Seventh Cohort of Vigiles, and crosses the Tiber at the Aemilian Bridge, close to Tiber Island. I mention all that because as I surveyed the house on arrival I was thinking, I bet the old Via Aurelia was the way Veleda fled on her escape. The Villa Quadrumatus lacked imposing steps, though it had a white marble portico that fully made up for that, set with very tall columns on a circular centrepiece, covered by a pointed roof. Pigeons had behaved disrespectfully on the big finial. It was too high for the household slaves to get up there on ladders and clean off the revolting guano more than once a year. If the steward was safety conscious, he probably made them build a scaffold when they had to do it – which I guessed was when they held their annual party to celebrate the master's birthday and invited half the Senate for a feast at which, undoubtedly, they had a full orchestra and a troupe of comedians, and served their own vineyard's Falernian specially brought up from Campania in ten ox wagons.

You see their style: Veleda, fresh from the dark forests of Germania, had been placed where she could witness the cream of Roman society in all their insane wealth. I wondered what she made of it. In particular, what she made of it once she realised these ostentatious persons would also one day be holding a glamorous garden party with two hundred guests, to celebrate the Ovation where she would be humiliated and killed… No wonder the woman took her chance and escaped. The door porter did not fail me. He was a thin Lusitanian in a tight tunic, with a flat head and a pushy manner, who spurned me before I had spoken a word: 'Unless you are expected, you can turn around and leave.' I gazed at him. 'Sir.'

My cloak, being my smart one, hung on a big brooch with a red enamelled pattern, on one shoulder. I threw the material back over the other shoulder in a nonchalant gesture, barely tearing any threads of the cloak. This enabled him to see me stick my fists in my belt. My grimy boots were planted apart on the washed marble. I wore no weapons, since going armed is illegal in Rome. That is to say, I wore none the door porter could see, though if he had any intuition he would realise that there might be a knife or a cudgel somewhere, currently invisible yet available to whop him with.

I had my civilised side. If he was a connoisseur of barbering, he would admire my haircut. It was my new Saturnalia haircut, which I had had two weeks early because that was the only time the decent barber at my training gym could fit me in. The timing suited me. I prefer a casual look at festivals. On the other hand, there was no point investing in a cripplingly expensive snip, with a slather of crocus oil, if porters still sneered at my locks and slammed the door.

'Listen, Janus. Let's not get off on a bad footing unnecessarily. You just go to your master and mention that I, Marcus Didius Falco (that's as in respected imperial agent) am here on the orders of Titus (that's as in Caesar) to discuss something very important, and while you (that's as in unmitigated ning-nong) are off on your errand, I'll try – because I am a generous man – to forget that I would like to tie your scraggy neck in a double clove hitch knot.' Titus' name worked like a love charm. I always hate that. While the porter disappeared to make enquiries, I noted that there were two very large cypress trees in four-foot pots like round sarcophagi, one either side of the twelve-foot-high double entrance doors. Either the Quadrumati liked their Saturnalia greenery to be very sombre, or there was another cause: somebody had died. M. Quadrumatus Labeo, son of Marcus, grandson of Marcus (a consul), had a bulbous shape hung about with a flowing long-sleeved robe, embroidered all over with lotus blossoms, which carried unexpected hints of Alexandrian decadence. I reckoned the pharaonic cuddler was worn for warmth; he was of straight deportment otherwise. A couple of enormous gold rings forced him to hold his hands rather stiffly so people would notice the metalwork, but his general manner was austere. His personal barber kept his hair clipped like a boxer, shaved him until his cheeks were the colour of crushed damsons, then splashed him with a light orris water.

I knew from prior enquiries at the Atrium of Liberty records office, his family had been in the Senate for at least three generations; I had been too bored to trace them any further back. It was not clear how this family had acquired their money, but I deduced from their home situation they still owned pleasant quantities. Quadrumatus Labeo could well have been a jovial fellow who kept his household in stitches with his witty stories, but when I first met him he was preoccupied and looked nervy.

The reasons for this emerged straight away. He was accustomed to business meetings, which he probably chaired with dispatch. He knew who I was. He told me what I needed, without waiting for questions: he had accepted Veleda into his house as a patriotic duty, though he was reluctant to have her for long and had intended to make representations for her removal (which I fancied would have been successful). They had made her comfortable, within reason, given that she had once been a ferocious enemy and was now a captive with a death sentence. His house was large enough to hide her away in a self-contained suite. There had been minimal contact between Veleda and his family, though his gracious wife had extended the courtesy of taking mint tea with the priestess in the afternoons.