I waited. He had second thoughts. 'He was called out from dinner to speak to somebody he knew.'

'See who it was?'

'No. He was only away for a moment. I suppose,' decided the priest, who was so pleased with his powers of deduction that he managed to slow down, 'Longinus put off their meeting until later tonight!'

'Here at your Temple! Seems likely. How do you know the mystery person was a man?'

'My servant told Curtius Longinus his visitor's name.'

I breathed a gentle prayer of thanks to Hercules. 'Help yourself and your Temple; tell me…'

We stopped on a corner by a fountain that glugged from the private orifices of a melancholy river god.

'How would it help?' fretted the priest.

'When our gracious new Emperor plans his civic rebuilding programme. Rededicating temples gives an Emperor a good name!'

'I understood that the Treasury was struggling for cash-'

'Not for long. Vespasian's father was a tax collector; he has extortion in the blood.'

He had taken out his doorkey. 'You seem fairly free with the Emperor's unearned income!' he commented. 'Who are you?'

'The name's Didius Falco; I act for the Palace-'

'Ho!' He perked up to insult me. 'Why's an intelligent, good-natured son of Rome involved in such shady work?'

'That's what I ask myself! So tell me,' I nudged him again, 'who was this man Longinus knew?'

'Someone called Barnabas,' said the priest.

It was dark now, but since I knew he worked late I wore out more boot leather traipsing back to see Vespasian again.

I waited while he shooed out the flyswatters and winefixers who never expect to remain in an audience while anything interesting occurs. Then I waited again, while the high-handed secretarial types got their marching orders too.

Once alone, we both relaxed. I stretched out on an imperial reading couch and gazed at the vaulted ceiling twenty feet above. This room was faced with dark green Brescia panels, divided by pilasters in creamy travertine. The wall sconces were gilt; all shaped like clams; all lit. I was brought up in dark houses where the rafters grazed my curls; looming spaces in elegant colour schemes have made me feel uneasy ever since. I lay on the couch as if I was nervous my body would leave an unpleasant mark on its silk.

The Emperor leaned on one great elbow, scrunching apples. His square, tanned face had that crag of a nose and jolly uptilted chin you see on the coins, with the laughter lines around his eyes. What the average denarius fails to reveal is that Vespasian Augustus had discovered one good source of light relief in me.

'Well, Falco?' He frowned at his fruit. It looked a four-cornered, floury job probably from his own Sabine estate; he never paid for anything he could grow himself.

'Caesar, I'd hate the bog savages to get a good name, but for a really sweet apple Britain beats the world!'

Vespasian had a military career in Britain, which had taken a distinctly glorious turn. My British career was twenty years later, and not glorious at all. Someone like Anacrites was bound to have told him that.

For a moment the old man paused, as if my mentioning the small, crisp russets of Britain that explode on the tongue with such unexpected sweetness had struck old chords. If I had not hated Britain so badly, I might have felt a homesick pang myself.

'What happened at the Temple?'

'Bad news I'm afraid, sir. Curtius Longinus is dead. Luckily for him, cremation is the fashion for Roman funerals nowadays.' The Emperor groaned and pounded his reading couch with a great fist. 'Sir, there's a contract bonus for naming your opponents. Does that include finding the maniac who's frittering them?'

'No,' he said. He knew that was a serious blow to me.

'All the Empire admires Caesar's graciousness!'

'Don't be sarcastic,' he growled menacingly.

In some ways we two were ill-assorted. Vespasian Caesar was an up-country senator from a down-market family, but a traditional aristocrat. I was an outspoken, introverted rough-neck with an Aventine accent and no sense of respect. The fact we could work together successfully was a typical Roman paradox.

While he absorbed my news with an angry frown I took advantage of the lull to report the full story.

'Sir, the missing freedman I told you about had heard Longinus was in Rome. I'm certain they met. It looks as if the freedman caused the fire. Did Anacrites manage to track him down in the Transtiberina?'

'No. The freedman had packed his bags and broken camp. When he lit this fire he must have already been prepared to do a flit. That's clear premeditation. What's he playing at, Falco?'

'Either a crazy campaign of vengeance for his patron's death in jail-or some more dangerous development.'

'You mean, either Barnabas blamed Longinus for having Pertinax killed-or Longinus had to be silenced before he saw me tomorrow because of something he might say? Did Curtius Longinus cause the death of Pertinax?'

'No, sir. The man I dropped in the Great Sewer for you this morning probably arranged that.'

'So what could Longinus have had to tell me?'

'I don't know. Perhaps his brother can enlighten us.'

The big man brooded glumly. 'Falco, why do I gain the impression that the moment we bury one conspiracy, a new one crawls to light?'

'I suspect because one has.'

'I'm not the type to waste my time running in fear of assassins.'

'No, sir.'

He grunted. 'I need you for something, Falco,' he offered. 'This reflects very badly on my administration-I want people to know I send for them in good faith! It's unsafe to invite the other Curtius brother to Rome, but someone had better get down there fast to warn him. There's not much involved. Carry him my condolences. Remember he is a Senator; they are an old family, of good standing. Just tell him what happened, put him on his guard, then ask him to write to me-'

'A messenger boy! Caesar, you asked me to work here! Yet I have to squeeze out commissions like drips from a dry cow-' The look on his face stopped me. 'What about warning the yachtsman Crispus in Neapolis?'

'Fancy bearding him on his boat?'

'Not much; I get seasick, and I can't swim. But I want real work to wrestle with.'

'Sorry,' he shrugged, crabbily offhand. 'Anacrites is looking forward to the seaside breezes serving that writ.'

'So Anacrites gets to gambol in the playgrounds of the rich, while I do three hundred miles on the back of a frisky mule then take a sock on the jaw when I tell Gordianus how he was bereaved?. Caesar, am I at least empowered to negotiate for his return? What you call offering "a favour he cannot forget"? What if he asks me about it? What if he tells me what he wants?'

'He won't, Falco-well if he does, use your initiative.'

I laughed. 'What you mean, sir, is that I have no meaningful authority; if I do win him over some snooty court chamberlain may thank me, but if anything goes wrong I am all on my own!'

Vespasian nodded drily. 'That is called diplomacy!'

'I charge extra for diplomacy.'

'We can discuss that if your attempt works! The challenge,' he explained more quietly, 'is to find out from Curtius Gordianus why his brother Longinus has got himself killed.'

Into his last apple now, he queried, 'Are you free to leave Rome at once? How are you coping with the Pertinax estate?'

'Quite a good house clearance! The luxury stuff has all been dispersed; we're doing table sales in flea markets now: job lots of jugs with loose handles and dented custard pans. Even the best homes turn up basketfuls of blunt old knives with none that match-' I stopped, because from what I had heard this sounded like the kitchen sideboards in Vespasian's family house before he became Emperor.