If he drew an unexpected breath, he disguised it well. `I congratulate you both!' Titus Caesar had the knack of sounding as if he meant exactly what he said.

`Thank you, sir,' I replied, a mite sombrely.

There was a small pause. Titus gazed at the dimly visible topiary. I restrained any urge to feel smug. Putting one over on the Emperor's elder son was not clever. Everyone knew Titus had a very pleasant temperament, but he could also have me sent down to Hades by the short route.

`This will be a difficult time for you, Falco. Is there anything I can do to assist?'

`I don't think so, sir. I did once make Helena and her parents a rather rash promise to improve myself socially and marry her but your brother tells me the equestrian rank is to be kept select, and I am not the right material.'

`Domitian said so?' Titus appeared unaware of it. I didn't blame him. Rome was full of eager self improvers; he could not expect to keep daily track of all of us. However, it might have been sensible to watch the ones that his family had kicked in the teeth.

`Obviously, you will not wish to overrule your brother, sir.'

`Oh obviously not,' Titus agreed, though I detected exasperation that his brother had chosen to antagonise me. He was publically loyal to Domitian, but his private opinion might be interesting. `So you have been having a bad time lately? I discover you went to Nabataea, on the state's behalf, and encountered difficulties?'

`There was no difficulty with Nabataea,' I told him. `Only with the shark who sent me there.'

`Anacrites! I'd like to hear your side of the story sometime,' Titus offered in a friendly tone. That left me worrying exactly what side of the story Anacrites had already told. I said nothing. Titus had known me long enough to realise when I was angry. Sometimes complaints have more effect if you make people sweat. `My father would welcome a report – if you will consider it.' I love to see a prince pleading. `We do need a confidential assessment of the situation in the desert.'

I smiled. Without a word, I produced a slim scroll from my tunic. Helena, smart girl, had not only forced me to write up my findings, but tonight she had guessed that I might find occasion to hand in my homework. This way Anacrites took no credit. He would not even know what I had said.

`Thank you,' said Titus gently, balancing the scroll between his well-manicured fingers. `You always serve us well, Falco. Both my father and I have a high opinion of your judgement and trustworthiness.' In fact they hated informers, and only used me when desperate. This must be leading somewhere. `Do you want to tell me about the problems you encountered?'

It was an invitation to land Anacrites in mule dung. Needless to say I took the sophisticated option: sheer stupidity. `It's not important, Caesar. I survived.'

`I think it is important.' Titus was acknowledging that spies receive speedy justice in hostile foreign kingdoms. `You were sent incognito and somebody accidentally exposed you.' `Deliberately exposed me,' I corrected in a mild tone. `Do you want an enquiry into that?'

'Best not find out,' I sneered. `Anacrites is too dangerous to dismiss. Better for him the telling demotion: say, conducting a very long survey of ordering procedures for sanitary materials in the public works domain.'

Titus had always privately enjoyed my cynicism. He ran both hands through his neat hair. `Falco, why is it when I talk to you I always end up wondering whether I can stand the pace?' He knew why. He was the Emperor's son, and would be Emperor himself. Few people would ever again offer him a decent argument.

`I'm a sterling debater, Caesar.'

`And modest!'

I produced a gracious shrug. `And the only kind of fool who'll risk offending you.' He accepted it, and laughed.

`And have you been paid for your work?' Titus then asked narrowly. Whatever Vespasian and he wanted from me next must be spectacularly unpleasant.

`Please don't trouble yourself. When the omens are right for the accounts clerks I shall draw my standard fee, Caesar.' `There will be an addition,' Titus remarked.

`That's most kind.' I was convinced something big was coming.

The pleasantries had been cleared away. Titus admitted that there was a reason why I had been summoned at night, without any record-takers present. He said the matter was confidential and sensitive; I could have guessed both. However, I had not guessed what I was being asked to undertake. And when I knew, I hated it.

`What I am going to say to you must remain a complete secret. Nobody – nobody, Falco, however close to you – is to be told what we discuss.'

I nodded. You commit yourself to this kind of nonsense like a lamb. That's the trouble with secrets. Until you know what they are, how can you tell whether your ethical element approves of them?

`Marcus Rubella,' Titus began crisply, `is a recent appointment to the tribunate of the vigiles.' Quite so. Vespasian's man. The city cohorts must be reckoned to be fairly loyal, since even while his predecessor and rival, Vitellius, had ruled Rome, Vespasian's brother Sabinus had been Prefect of the City. Sabinus, a popular man trying to keep the peace in impossible times, inspired lasting respect. To reinforce that, officers throughout the civil institution, in Rome were now, like those in the legions, being changed as the new Emperor handed out rewards and replacement where applicable.

`I met Rubella,' I said conversationally.

`I know that,' Titus said. A bad feeling was already creeping over me.

`Seemed an interesting character.'

Titus smiled. `That must be some kind of cautious shorthand – Rubella said much the same about you.' So, since interviewing me only that morning, Marcus Rubella, the tribune of Petro's cohort, had been talking to Titus. Another evil sensation hit me somewhere in the lower gut.

`This is rather unpleasant,' Titus explained inexorably. `Rubella is disturbed about the low level of ethics amongst his men.'

Of course I had seen it coming, but I drew a harsh breath. `Rubella thinks the Fourth accept bribery?'

`Does that surprise you, Falco?'

`I know one of them,' I confessed.

`I am aware of that.'

`I know him well.'

`And?'

And I could not stomach the suggestion that Petro might even be under suspicion. `It's impossible.' Titus was waiting for me to elaborate. `The man I know, my friend Lucius Petronius, is an impeccable character. You saw him at the meeting yesterday; you must have judged his quality. He is the man who has just expelled from Rome a major criminal. Balbinus Pius would never have been brought to justice without him.'

`True. Were it not for that,' Titus said, `he would be under a cloud with the rest, and there would be no question of asking you to assist us. We are assuming that Petronius Longus need not feature in Rubella's concern. However, Petronius must not be made aware of our enquiries until he is formally ruled out, and perhaps not even then.'

`This stinks,' I said. `You want me to spy on the Fourth-'

'Not only them,' Titus broke in. `Your special assignment is to involve any relevant regions of the city. What Rubella has reported about his own cohort may apply elsewhere – his may not even be the worst problem. I want you to take a close look at any cohort you come into contact with.'

That was better. I had already gathered from Petro a feeling that some of the rest were much less choosy in their habits than his own team. But if I was not allowed to tell him what I was doing, it would be difficult to pry this kind of information from him. If I was underhand and he found out later, he would be outraged. Rightly so.

`Sir, this could damage my most valued friendship.'

`I apologise if so. But I believe you are capable of handling it.' Oh thanks! `You were selected as particularly suitable. In fact, we have been awaiting your return from the East.'