`Interesting question.' In fact there could be several reasons why the Emperor might feel a foreign jail was just the place for me. I was an upstart who wanted social promotion; since he disapproved of informers, the idea of letting me wear the gold ring and strut like a man of substance had always rankled. Most of the time he owned me money for my undercover services; he would love to renege. Then one of his sons had tender feelings towards a certain young lady who preferred to live with me, while I had a long-term feud with the other. Either Titus or Domitian might have asked their pa to dump me. Besides, who really likes a hireling who handles problems with dispatch, then comes back wearing a happy smile and expecting a huge cash reward?

`I don't know why you work for him,' Petronius grumbled angrily.

`I work for myself,' I said.

`That's news!'

`That's the truth. Even if the damned secretariat offers me a straight task with a set fee and vast expenses, I won't consider it. From now on, I stick to private commissions – which was what I had to do after I got shoved in shit in Arabia by bloody Anacrites and his devious games.'

`You're a dope,' Petro answered disbelievingly. `You can't resist the challenge. One nod from the man in purple and you'll scuttle back.'

I grabbed the flagon and helped us both to more wine. It still tasted like a cure for swine fever. `Petro, the man in purple didn't try to sell me to a camel trader.'

Whatever I thought of the rank of emperor, Vespasian the man was completely straight. Even Petronius grudgingly allowed the point. `So it was the spy, Falco. What's the difference?'

`Who knows? But Anacrites thinks I'm rotting in some desert citadel; this could be the lever I'm looking for to show him up. I'll give my travelogue to Vespasian before the spy finds out I'm alive and back in Rome.'