The scene is set in Rome, in the Circus of Nero and in a small back room at the Palace of the Caesars on Palatine Hill. The time is

SYNOPSIS: Helena, daughter of Camillas, is a young girl disappointed by Falco, a trickster, who seemed to have promised her marriage. He now claims he has been let down by Vespasian, an Emperor, his patron. In the nick of time Thalia, a high-class entertainer, and Anacrites, a low-class spy, both suggest ways in which Falco may escape from this predicament, but he must prevent Helena discovering what he is up to, or a Chorus of Disapproval is bound to ensue.

'Somebody could get killed here!' Helena exclaimed.

I grinned, watching the arena avidly. 'That's what we're meant to be hoping for!' Playing the bloodthirsty spectator comes easy to a Roman.

'I'm worried about the elephant,' she murmured. It stepped tentatively forwards, now at shoulder height on the ramp. A trainer risked tickling its toes.

I felt more concern for the man at ground level who would catch the full weight if the elephant fell. Not too much concern, however. I was happy that for once the person in danger was not me.

Helena and I were sitting safely in the front row of Nero's Circus, just across the river outside Rome. This place had a bloody history, but was nowadays used for comparatively staid chariot racing. The long circuit was dominated by the huge red granite obelisk that Caligula had imported from Heliopolis. The Circus lay in Agrippina's Gardens at the foot of the Vatican Hill. Empty of crowds and of Christians being turned into firebrands, it had an almost peaceful atmosphere. This was broken only by brief cries of 'hup!' from practising tumblers and rope dancers and restrained encouragement from the elephant's trainers.

We were the only two observers allowed into this rather fraught rehearsal. I happened to know the entertainment manager. I had gained entrance by mentioning her name at the starting gates, and was now waiting for a chance to talk to her. Her name was Thalia. She was a gregarious character, with physical attractions that she did not bother concealing behind the indignity of clothing, so my girlfriend had come to protect me. As a senator's daughter, Helena Justina had strict ideas about letting the man she lived with put himself in moral danger. As a private informer in an unsatisfactory job and with a shady past behind me, I suppose I had asked for it.

Above us soared a sky that a bad lyric poet would certainly have called cerulean. It was early April; midmorning on a promising day. Just across the Tiber everyone in the imperial city was twisting garlands for a long warm springtime of festivals. We were well into the third year of Vespasian's reign as Emperor, and it was a time of busy reconstruction as burnt-out public monuments were rebuilt after the civil wars. If I thought about it, I was in a mood for some refurbishment myself.

Thalia must have despaired of proceedings out in the arena for she threw a few harsh words over a barely decent shoulder, then left the trainers to get on with it. She came over to greet us. Behind her we could see people still cajoling the elephant, who was a very small one, along the ramp that was supposed to bring him to a platform; from this they had hopefully stretched a tightrope. The baby elephant could not yet see the rope, but he knew he did not like what he had discovered about his training programme so far.

At Thalia's arrival my own worries became wilder too. She not only had an interesting occupation, but unusual friends. One of them lay around her neck like a scarf. I had met him at close quarters once before, and still blenched at the memory. He was a snake, of modest size but gigantic curiosity. A python: one of the constricting species. He obviously remembered me from our last meeting, for he came reaching out delightedly, as if he wanted to hug me to death. His tongue flickered, testing the air.

Thalia herself took careful handling. With commanding height and a crackling voice that cut right across this huge arena, she could always make her presence felt. She also possessed a shape few men could take their eyes off. Currently it was draped in silly strips of saffron gauze, held in place by gigantic jewellery that would break bones if she dropped any of it on your foot. I liked her. I sincerely hoped she liked me. Who wants to offend a woman who is sporting a live python for effect?

'Falco, you ridiculous bastard!' Being named after one of the Graces had never affected her manners.

She stopped in front of us, feet planted apart to help support the snake's weight. Her huge thighs bulged through the flimsy saffron. Bangles the size of trireme rowlocks gripped tightly on her arms. I started to make introductions, but nobody was listening.

'Your gigolo looks jaded!' Thalia snorted to Helena, jerking her head at me. They had never met before but Thalia did not trouble with etiquette. The python now peered at me from her pillowing bosom. He seemed more torpid than usual, but even so something about his disparaging attitude reminded me of my relatives. He had small scales, beautifully patterned in large diamond shapes. 'So what's this, Falco? Come to take up my offer?'

I tried to look innocent. 'I did promise to come and see your act, Thalia.' I sounded like some stuffed green fig barely out of his toga praetexta, making his first solemn speech in court at the Basilica. There was no doubt I had lost my case before the usher set the water clock.

Thalia winked at Helena. 'He told me he was leaving home to seek employment taming tigers.'

'Taming Helena takes all my time,' I got in.

'He told me,' Helena said to Thalia, as if I had never spoken, 'he was a tycoon with big olive vineyards in Samnium, and that if I tickled his fancy he would show me the Seven Wonders of the World.'

'Well, we all make mistakes,' Thalia sympathised.

Helena Justina crossed her ankles with a swift kick at the embroidered flounce on her skirt. They were devastating ankles. She could be a devastating girl.

Thalia was giving her a practised scrutiny. From our previous encounters Thalia knew me to be a low-life informer, plugging away at a dismal occupation in return for putrid wages and the public's contempt. Now she took in my unexpectedly superior girlfriend. Helena was posing as a cool, quiet, serious person, though one who could silence a cohort of drunken Praetorians with a few crisp words. She also wore a stunningly expensive gold filigree bracelet that by itself must have told the snake dancer something: even though she had come to the Circus with a dried melon seed like me, my lass was a patrician piece, backed up by solid collateral.

Having assessed the jewellery, Thalia turned back to me. 'Your luck's changed!' It was true. I accepted the compliment with a happy grin.

Helena gracefully rearranged the drape of her silken stole. She knew I didn't deserve her, and that I knew it too.

Thalia gently lifted the python from her neck, then rewound it around a bollard so she could sit down and talk to us. The creature, which had always tried to upset me, immediately unravelled its blunt, spade-shaped head and stared balefully with its slitted eyes. I resisted the urge to pull in my boots. I refused to be alarmed by a legless thug. Besides, sudden movement can be a mistake with a snake.

'Jason's really taken to you!' cackled Thalia.

'Oh, he's called Jason, is he?'