Petronius, who was very straightforward in certain respects, looked appalled. 'You never believe that!'

'I don't know what I believe.'

I did know. What I really thought was worse.

I gave them one last glance as they stood there, both furious, and both allied against me. Then I left.

Convincing myself I might not be this baby's father was insulting to Helena and demeaning to myself. Yet it was easier than the truth: look at what I was. Look at how I lived. I could not blame her for an instant if Helena Justina refused to bear a child of mine.

She had, without me knowing it, already told me what she planned to do. She would 'deal with it'; I could still hear her saying so. That could only mean one thing.

I filled in the rest of that afternoon by accepting I had a hangover, and going home to sleep it off.

LXXX

Lying in bed is never entirely wasted. Somewhere in that void between convincing yourself you are awake and then ages later rousing yourself, I devised a plan for picking up the trail on Pertinax. I dug out a tunic I used to like; it had been mauve once but was now unappealingly light grey. I went to the barber's for a really good shearing. Then, merging anonymously into the throng, I set off.

At the magic hour just before dinner I crossed the Tiber on the Aurelian Bridge. I was alone. No one knew where I was going, or would notice if I failed to return. None of the people who might once have cared to do so would be bothering to remember me tonight. So far, curing a headache had been the most productive aspect of my day.

Days change. In my case, usually for the worse.

Smoke from a thousand bath-house furnaces drifted across the city. It caught my throat, calling to life the unhappy rasp that was already lurking there. By now, Helena Justina would know I was back in Rome, aware of her plight. Her father was bound to have told her how deeply hurt I felt. As I expected, she made no attempt to contact me. Not even though I had made it easy for her by spending most of the day at home in bed.

Crossing the river, I listened to the ripple of refined applause from a performance in Pompey's theatre-not the ripe jollity of a satyr play or even the gasps and cheers that greet arthritic monkeys on tightropes. Tonight it must be something old, possibly Greek, probably tragic, and definitely reverent. I was glad. It suited my mood to think of other people suffering: three hours of sombre stuff from the chorus, a tight little speech or two from a principal actor fresh out of elocution class, and then, just as you get to the good bit with the blood, your honeyed dates fall down into the row in front, so you have to bend forwards to grab them again before some shopkeeper with enormous buttocks sits back and squashes them-and as you lean down to get them you miss the only excitement in the play…

Tough. If you want entertainment, stay in and pick fleas off a cat.

•

The Aurelian Bridge was not the most straightforward route to where I was going, but tonight was for choosing long ways round and losing my way. Cursing blind beggars. Bumping old grandmothers into the gutter. Stepping in games of draughts chalked on the pavement while the players were still using them. Losing face. Losing grace. Hurting my toe trying to kick a hole in the stubborn travertine parapet of an ancient bridge.

The Transtiberina fills up by night. During the day it disgorges its populace over the river to hawk contaminated pies, damp matches, sinister green necklaces, good-luck charms, curses, the use of the salesman's sister for five minutes in the crypt of the Temple of Isis at half an as a go (and if you catch something incurable, don't be surprised). Even the solemn, dark-eyed children disappear from the streets of their own sector to play their special kind of tag-lifting purses from unwary pockets around the Cattle Market Forum and along the Sacred Way (where nothing is sacred nowadays, though perhaps not much ever was).

At night back they all come, like dark effluent seeping silently into the warrens of the Fourteenth. The thin men swinging armfuls of belts and rugs. The hard-eyed women who fix you with demands for their twisted sprigs of violet or cracked bone amulets. Those children again, with their sad, beautiful, vulnerable expressions-and unexpected catcalls of obscene abuse. By night the Transtiberina swells even more richly with the exotic. Above the warm aura of oriental flavourings rises the murmurous music of foreign entertainments carried on behind barred doors. Hard gambling for small sums, but a lifetime's misery. Casual lechery being served at a high price. The thump of a tabor. The shiver of tiny brass bells. To the walker a shutter swinging stealthily overhead in the dark is as dangerous as the door which flies open abruptly, spilling light, and a manic knifeman, onto the street. Only an informer with the kind of brain disorder that needs his doctor to send him on a six months' sea cruise with a huge bottle of purgatives and a fierce course of exercise goes into the Transtiberina alone at night.

Still, in I went.

These places never look the same a second time. When I finally found the street I wanted it was as small and as narrow as I remembered, but the wineshop had put two tables outside and in the blank grey walls that faced the alley one or two lockups I had never even noticed during the siesta had now pushed back their wooden fronts for the evening trade. I strolled up to a pastryshop, then leaned against its awning pole as I gnawed my way through a hunk of their handiwork and considered the deadly stodginess of foreign cakes. It was spherical, about half the size of my fist; it had the hard-packed consistency of my sister Junia's home-trade meatballs, but all the flavour of an old horse-blanket. As it went down, which it did very slowly, I could feel my startled guts expressing moral outrage every inch of the way. I could have dumped it in a drain, but it might have caused a blockage. Anyway, my mother had brought me up to hate wasting food.

I had plenty of time to pretend I was chewing through my sweet-meat, savouring one or two little hard bits that were either nuts or well-roasted woodlice who had sidled into the cake dough. Meanwhile I discreetly eyed up the first-floor window of the room which the so-called freedman Barnabas had once leased.

The window was too small and the housewalls were too thick to see much, but I could just make out the shadow of at least one person moving about inside. An unusual stroke of luck.

I was licking my fingers when the street door opened suddenly and two men came out. One was a chatty scallywag with an inkpot hung on his belt who looked like a scribe on piecework. The other, ignoring his companion's flow of natter as he glanced surreptitiously up and down the alley, was Pertinax.

He had learned to look around him, though not to see; if I was near enough to recognize him-the light, ruffled hair and the pinched nostrils in that agitated face-then even in a scalped hairstyle and a new-coloured tunic he should have known me too.

On the threshold they shook hands and went their separate ways. I let the inkpot pass me, heading off the way I had come myself, then I prepared to go after Pertinax. It was lucky I was slow. Two men who had been playing a sluggish game of soldiers at one of the tables outside the wineshop pushed away the board and counters and then stood up. Before Pertinax reached the streetcorner, they also began to move-after him, and just ahead of me. They too separated: one speeded up until he overtook Pertinax while the other loitered behind. As the man who was dawdling reached the corner he met another quiet figure in the wider street beyond. With sudden intuition I had stepped into a doorway. When numbers two and three joined forces I was near enough to overhear their low exchange.