'What is Vespasian's interest in Petra?' The Brother asked. His eyes were sly, deceptive slits in that passionless face. A man so astute must know exactly what Rome's interest would be in a rich nation that controlled important trade routes just outside our own boundaries.

I can argue politics as fiercely as the next man who is standing around the Forum with two hours to fill before dinner, but I did not relish putting the Empire's point of view in a foreign city. Not when nobody at the Palace had bothered to instruct me what the Empire's foreign policy was supposed to be. (Nor when the Emperor, being pedantic about such trifles, was likely to hear about my answer sooner or later.) I tried to escape. 'I can't answer you, sir. I'm just a humble information-gatherer.'

'Not so humble, I think!' It sounded elegant in Greek, but was not a compliment. He could sneer without the slightest change of expression.

The Brother folded his arms, still staring down at the dead man lying at our feet. Water from the sodden body and its clothing had seeped into the paving. Every fibre within the cadaver must be growing cold; soon flies would be coming to look for egg-laying sites. 'What is your quality? Do you have many possessions?'

'My house is poor,' I answered. Then I remembered Helena reading out to me a passage from a historian who said the Nabataeans particularly prized the acquisition of possessions. I managed to make my remark sound like polite modesty by adding, 'Though it has seen feasting with the son of the Emperor.' The Nabataeans were supposed to enjoy a good feast, and most cultures are impressed by men who dine freely with their own rulers.

My information left The Brother looking thoughtful. Well it might. My relationship with Titus Caesar had its puzzling aspects, plus one that was perfectly clear: we both hankered for the same girl. Unsure of the Nabataean attitude to women, I kept quiet on this subject.

I thought about it aplenty. Every time I went somewhere dangerous abroad, I wondered if Titus was hoping that I never came back. Maybe Anacrites was not merely plotting to get rid of me for his own reasons; perhaps he had sent me here on prompting from Titus. For all I knew, the Chief Spy's letter to The Brother had suggested that Titus Caesar, the heir to the Empire, would deem it a personal favour if I stayed at Petra for a very long time: for ever, for instance.

'My visit has no sinister implications,' I assured Petra's minister, trying not to look depressed. 'Rome's knowledge of your famous city is somewhat thin and out of date. We rely on a few very old writings that are said to be based on eye-witness reports, chief among them an account by Strabo. This Strabo had his facts from Athenodorus, who was tutor to the Emperor Augustus. His value as an eye-witness may be tempered by the fact that he was blind. Our sharp new Emperor distrusts such stuff.'

'So Vespasian's curiosity is scholarly?' queried The Brother.

'He is a cultured man.' That was to say he was on record as once quoting a rude line from a play by Menander concerning a chap with an enormous phallus, which by the standards of previous emperors made Vespasian a highly educated wit.

But it was Vespasian the crusty old general who must preoccupy foreign politicians. 'True,' The Brother pointed out. 'But he is also a strategist.'

I decided to stop feinting. 'And a pragmatic one. He has plenty to occupy his energies within his own borders. If he believes the Nabataeans are interested only in pursuing their own affairs peacefully, you can rely on it that he will elect, like his predecessors, to make gestures of friendship to Petra.'

'And were you sent to say that?' queried The Brother, rather haughtily. For once I saw him tighten his mouth. So the Petrans were afraid of Rome – which meant there were terms we might negotiate.

I lowered my voice. 'If and when Rome chooses to assimilate Nabataea within its Empire, then Nabataea will come to us. This is a fact. It is no treachery towards you, and perhaps not even an unkindness, to state it.' I was taking a lot upon myself here, even by my risky standards. 'I am a simple man, but it seems to me that time is not yet here. Even so, Nabataea might do well to plan ahead. You lie in an enclave between Judaea and Egypt, so the questions are not w ill yon join the Empire, but when and on what terms. At present these are within your own control. A partnership could be achieved both peacefully and at a time that suited you.'

'This is what your Emperor says to me?' queried The Brother. Since I had been told by Anacrites to avoid official contact, I had of course been given no instructions about speaking for Vespasian.

'You will realise,' I confessed frankly, 'I am a fairly low-grade messenger.' The hooded eyes darkened angrily. One lean hand played with the jewelled dagger at his belt. 'Don't be insulted,' I urged him quietly. 'The advantage to you is that a higher-powered embassy would necessitate action. Important men sent on delicate missions expect results; they have careers to found. The day you find a Roman senator measuring your civic monuments, you'll know he's trying to find a space for a statue of himself in a laurel wreath, looking like a conqueror. But any report I make can be filed away in a casket if Vespasian wants to preserve the status quo.'

'Assuming you make a report!' The Brother rejoined, going back to the fun of threatening me.

I was blunt. 'Best that I do. Pegging me out on top of one of your crow-step altars could rebound on you. The peremptory death of a Roman citizen – which I am, despite shabby appearances – might be a neat excuse for sending in a Roman army and annexing Nabataea immediately.'

The Brother smiled faintly at this idea. The death of an informer, travelling without official documents, was unlikely to justify world-scale political initiatives. Besides, Anacrites had told him I was coming. Apart from his personal hatred of me, in diplomatic terms that was probably meant as a warning to the Nabataeans: Here's one observer you know about; there may be others you fail to detect. Rome feels so confident, she's even spying on you openly.

My own fate was not a diplomatic issue. Anyone who took a dislike to my face could safely cast my corpse on their local rubbish tip. Accepting it, I smiled back peacefully.

At our feet the man who really was dead still waited for attention.

'Falco, what does this unknown body have to do with you?'

'Nothing. I found him. It was coincidence.'

'He brought you to me.'

Coincidence has a habit of landing me in tight situations. 'Neither the victim nor his killer knew me. I have merely reported the incident.'

'Why did you do that?' enquired The Brother sedately.

'I believe his killer should be traced and brought to justice.'

'There are laws in the desert!' he rebuked me, his deep voice soft.

'I was not suggesting otherwise. For that reason I alerted you.'

'You may have wished to remain silent!' He was still niggling about my role in Petra.

Reluctantly I conceded: 'It might have been more convenient! I'm sorry if you have been informed I'm a spy. To get this in perspective, let me tell you that your helpful informant is also the man who paid me to come here.'

The Brother smiled. More than ever he looked like somebody you wouldn't trust to hold your purse while you were undressing at the baths. 'Didius Falco, you have dangerous friends.'

'He and I were never friends.'

We had stood talking in the open outdoor area for much longer than could be customary. At first it must have appeared to the onlookers that we were speculating about the dead man. Now people in the crowd were growing restless as they sensed more going on.

This corpse had become a useful cover for The Brother. It could well be that at some future date the sensible Nabataeans would hand themselves over to Rome on negotiated terms – but there would be ample preparation. No disturbing rumour would be permitted to ruffle commerce prematurely. At this stage The Brother needed to hide from his people the fact that he had been talking with an official from Rome.