The Circus of Caligula and Nero-as lurid a pair of characters as you could meet at the back of a bathhouse -lies opposite the great right-hand bend of the river which encloses the Plain of Mars. As luck would have it, there were no races that week but there was a small exhibition of caged wild animals, surrounded by the usual nervous schoolboys wondering if they dared throw things, a little girl who wanted to pat a tiger, and a desultory trainer who rushed out from time to time to warn people away from the bars. On show were a hippopotamus, the inevitable elephant, two ostriches, and a Gallic lynx. There were a few bales of wet, dirty straw and a sad smell.

The showfolk owned some canvas booths in the shadow of the starting gates; as I went past to enter the Circus, I overheard a familiar female voice relating some tawdry tale. '... I thought he had just gone for a tinkle with his winkle, but he was hours; anyway I forgot all about him-why bother?-but when I went to feed the python, there he was; he must have stripped for action before he saw the snake -I found him cowering up against the awning, too scared to shout-all knobby knees and his poor little set of equipment dangling there like a three-piece manicure set...'

I pulled back a battered curtain and beamed. 'I shall never be able to look at an earscoop again! Thalia! How's the performing snake business?'

'Falco! You still trying to run away from home to do something adventurous? How did you know it was me?'

'Oh-I think I've met a parrot you must have known at one time ...'

'That terrible bird!' she said.

Her companion - a thin specimen who must be the woman who fed the man who watered the hippopotamus -gave me a prim smile, and slipped out of the booth.

Thalia became more serious. 'You're dressed up like a messenger with bad news for somebody.'

'For villains, I hope. That talk we had the other day helped me a lot. Have you got a moment?'

'Let's get some air,' she suggested, perhaps afraid of being overheard.

She led me outside, and into the Circus. We paused slightly at the starting gates, where once the panther must have made its meal of Severina's husband Fronto. In silence Thalia and I climbed up a few rows and sat on the marble seats.

'I'm developing a theory about Fronto's death. Thalia, you said you never met his wife. So I suppose you wouldn't know whether Severina had a fancy man?'

'Couldn't say. But Fronto thought she did.'

'Did he suspect who?'

'I never heard a name. But Fronto seemed to believe there was someone she had known for a long time who could be hovering offstage.'

'That fits,' I said. 'She's mentioned a fellow slave from her original master's; she wears a ring he gave her. And a doctor who attended another of her husbands told me a "friend" came to comfort her afterwards. But there's no sign of this fellow anywhere now.' In fact when we were getting drunk together she had said he was in the Underworld. 'Tell me, Fronto and Severina were only together a few weeks. She seems to think badly of him. Did he knock her about?'

'Probably.'

'A rough type? All sweetness until they were married, then he cut up sour?'

'You know men!' she grinned. But then she added, 'Fronto didn't like to be made a fool of.'

'And he reckoned Severina had pulled a fast one on him?'

'Didn't she?' We sat brooding for a moment. 'Have I got to go to court, Falco?'

'Not sure.'

'Who would take care of my snake?'

'I'll try to keep you out of it... But I know a girl who's kind to animals, if it comes to anything.'

'I've been thinking about that stockman,' Thalia said, explaining why she was so worried about matters going further. 'I'm sure he came to work for us about the time Fronto got married-I can't be sure, but I had an idea that she persuaded Fronto to take him on.'

I smiled. 'That's the theory I've devised.'

'The thing is,' she told me slowly. 'I reckon I can remember the stockman's name now-'

'The mysterious Gaius?' I sat up straight. 'The one who let the panther out, who was then crushed by a falling wall?' Something else had clicked into place while we sat here quietly; details I had heard from Petronius: "Three children died when a floor fell in ... The Hortensii average a lawsuit a month ... A wall gave may and killed a man, somewhere on the Esquiline..." 'The name wouldn't be Cerinthus, I suppose?'

'You rotten bug-' Thalia accused me laughingly. 'You knew all along!'

I knew something else too. I now understand the real reason why Hortensius Novus died.

Time had gone by. It was dusk when I reached the Hortensius mansion, but its owners were so fond of displaying their lucre that they had already set up rows of resin torches and dozens of flickering lamps. As usual I ended up in a reception room which was completely new to me, alone.

The freedmen had bravely set aside their grief for Novus and were entertaining friends. There was a faint lick of perfumed garlands, and from time to time when a door opened I caught a distant swell of laughing voices with the shiver of a tambourine. The message which I sent in was framed to intrigue, with a warning beneath. A slave came back from Sabina Pollia asking me to wait. To while away the time while the company gorged she had me provided with a few titbits of my own: a feast, nicely presented on three silver trays, accompanied by a flagon of their well-aged Setinum wine. I discovered it was good quality because I was in no mood for tasting titbits so imbibing at least their Setinum seemed only polite.

On the wine tray were a matched pair of jugs with hot water and cold, a small charcoal burner, bowls of herbs, a pointed strainer, and fine twisted winecups of green Syrian glass: I amused myself for half an hour with these, men sat back on a couch decorated with silver lions and gazed thoughtfully about the vividly furnished room. It was too splendid to be comfortable but I had reached the stage where reclining amid tastelessness, despising it, suited my bitter mood.

Before long Sabina Pollia did appear. She was swaying slightly, and offering to serve me more wine with her own fair hands. I told her mine was a large one, leaving out the herbs and the water. She laughed, poured two, sat beside me, and then we both dashed off daring quaffs of Setinum, neat.

After days on an invalid diet, it tasted richer than I could handle. But I polished it off, swung to my feet and poured myself some more. I came back to sit beside Pollia. She laid one elbow on the back of the couch just behind my head, leaning on her hand as I gazed into her exquisite face. She smelt of some drowsy perfume squeezed from the glands of animals. She was slightly flushed and she watched me through experienced half-closed eyes.

'Have you something to tell me, Falco?'

I smiled lazily, admiring her at close quarters while her hand idly tickled my ear. The excellence of the wine burned comfortably into my windpipe. 'There are many things I could tell you, Sabina Pollia-most of them not relevant to the reason why I've come!' I drew my finger along the perfect line of her cheek. She gave no sign of awareness; I asked quietly, 'Do you and Atilia realise there are witnesses to what you tried to do with the poisoned cake?'

She grew very still. 'Perhaps Atilia should be here?' She spoke with neither embarrassment nor any other kind of feeling that I could recognise.

'As you wish.' She made no move to send for her crony, so I went on, 'Hortensia Atilia at least had the excuse that she thought she was providing for her young child. What about you?' Pollia merely shrugged. 'No children yourself?'

'No.' I wondered if that was a conscious choice to preserve her figure. Then she asked, 'Falco, have you come to threaten us?'