Simultaneously someone strode out from a great doorway cut through the enclosure wall. I never found out what lay behind it, whether the area beyond that impressive-looking portal housed the quarters of the priestly college, or was this high official's own stately residence. Somehow I knew he was important even before I looked at him directly. He carried the aura of power.

He was walking straight towards us. He was alone, but every man in the place was aware of him. Apart from a jewelled belt and a neat, high head-dress with a Parthian look to it, little marked him out. My priestly companion hardly moved or changed expression, yet I sensed a frantic upsurge of tension in him.

'Who is it?' I managed to mutter.

For reasons I could guess, the young man could barely croak out his answer. 'The Brother,' he said. And now I could tell that he was terrified.

I stood up.

Like most Nabataeans the Petran Chief Minister was shorter than me, and slighter. He wore the usual full-length, long-sleeved tunic with other robes in fine material folded back over his upper arms. That was how I could see the glittering belt. There was a dagger thrust through it, with a ruby set in the hilt that barely left room for the handle's ornate metalwork. He had a high forehead, his hair well receded under the head-dress, and his manner was energetic. The wide mouth gave an impression of smiling pleasantly, though I did not fall into the trap of believing it. He looked like a friendly banker – one with his heart set on diddling you on your interest rate.

'Welcome to Petra!' He had a deep, resonant voice. He had spoken in Greek.

'Thank you.' I tried to make my accent as Athenian as possible – not easy when you've been taught your Greek under a ripped awning on a dusty street corner near the neighbourhood middenheap.

'Shall we see what you have found for us?' It was like an invitation to open a basket of presents from an uncle in the country.

His eyes gave the game away. The lids were so deeply pouched and crinkled that no expression was visible in those dark, faraway glints. I hate men who hide what they think. This one had the difficult manner I normally associate with a vicious fornicating fraud who has kicked his mother to death.

We walked to the camel, which thrust its head towards us unnervingly. Someone grabbed the bridle, hissing at its disrespect for my companion. Two men lifted down the body, fairly gently. The Brother inspected the corpse just as I had done previously. It appeared an intelligent scrutiny. People stood back, watching him earnestly. Among the crowd I recognised the elder priest from the temple with the garden, though he made no move to contact his young colleague, who was now standing behind me. I tried to believe the youngster was there in case I needed support, but help seemed unlikely. I was on my own with this.

'What do we know of this person?' The Brother asked, addressing me. I gathered that I was expected to take responsibility for explaining the stranger.

I indicated the writing block at the dead man's waist. 'A scholar or clerk maybe.' Then I pointed to the grazes on the broad, slightly puffy face. 'He had clearly suffered violence, though not an extreme beating. I found empty drinking vessels at the scene.'

'This occurred at the High Place?' The Brother's tone was not particularly angry, but the careful posing of the question spoke volumes.

'Apparently. Seems to be some drunk who fell out with his friend.'

'You saw them?'

'No. I had heard voices, though. They sounded amiable. I had no reason to rush up after them and investigate.'

'What was your own purpose in visiting the Place of Sacrifice?'

'Reverent curiosity,' I stated. It sounded unconvincing and crass, of course. 'I had been told it is not forbidden?' it is not forbidden,' agreed The Brother, as if he thought that in a just world it should have been. Legislation seemed likely to emanate from his office later that afternoon.

I took a stand. 'I believe that is all the help I can give you.' My remark was ignored. If a foreign visitor foolishly came across a drowned man in the Basin of Fundanus in Rome, he would be thanked for his sense of civic duty, given a public reward of modest proportions, and led quietly out of town-or so I told myself. Maybe I was wrong. Maybe he would be flung into the worst jail available, to teach him not to malign the Golden Citadel with sordid discoveries.

The Brother stood back from crouching over the corpse. 'And what is your name?' he enquired, fixing me with those pleasant dark eyes. From deep in their wrinkled pouches of weariness those eyes had already noted the cut of my tunic and style of my sandals. I knew he knew that I was Roman.

'Didius Falco,' I answered, with a more or less clear conscience. 'A traveller from Italy – '

' Ah yes!' he said.

My heart sank. My name was already known here. Somebody had warned the King's Chief Minister to expect me. I could guess who it was. I had told everyone at home that I was going to the Decapolis on a seek-and-retrieve for Thalia's water organist. Apart from Helena Justina, only one person knew I was coming here: Anacrites.

And if Anacrites had written ahead to the Nabataeans, then as sure as honey makes your teeth rot, he wasn't asking The Brother to extend me any diplomatic courtesies.

I would have liked to punch The Brother in the solar plexus and make a run for it. If, as I guessed, he was hated and feared in Petra, then the crowd might let me through. If he was hated and feared even more than I suspected, however, it might be to their advantage to avert his wrath by stopping me.

We Romans are a civilised nation. I kept my fists at my sides and faced him out. 'Sir, I am a man of humble origins. I am surprised you know of me.' He made no attempt to explain. It was vital that I found out his source of information, and quickly. There was no point trying to bluff. 'Can I guess that you heard about me from a functionary called Anacrites? And did he ask you to put me top of the list for sacrifice in Dushara's High Place?'

'Dushara requires immolation only from the pure!' commented The Brother. He had a gentle line in sarcasm -the most dangerous kind. I was in a tricky situation here, and he liked the fact that I was aware of it.

I noticed him make a surreptitious gesture to tell the surrounding crowd to stand off somewhat. A space promptly cleared. I was to be interrogated with a modicum of privacy.

Ignoring the disturbance, I answered him lightly: 'No doubt Petra has other quick and easy systems of disposal?'

'Oh yes. You can be laid out on an offering block for the birds and the sun.' He sounded as if he would enjoy giving the order. Just what I always wanted: to die by being frizzled like offal, then picked clean by a clan of vultures.

'I look forward to the privilege! And what have you been told about me?'

'Naturally that you are a spy.' He appeared to be making a polite joke of it. Somehow I felt no urge to grin at the pleasantry. That was information on which he would certainly act.

'Ah, the usual diplomatic nicety! Do you believe it though?'

'Should I?' he asked, still giving me the dubious courtesy of appearing open and frank. A clever man. Neither vain nor corrupt: nothing to bite back against.

'Oh I think so,' I replied, employing similar tactics. 'Rome has a new emperor, an efficient one for once. Vespasian is taking stock; that includes surveying all the territory which borders on his own. You must have been expecting visitors.'

We both glanced down at the body. He deserved more personal consideration. Instead, some tawdry domestic quarrel had made him an opportunity for this unexpected high-flown discussion of world events. Whoever he was, he had wound himself into my mission. His fate was welded to mine.