'Do you think they'll be apprehended?'

'Probably not.'

'How do you know he was a centurion?'

'He wore his sword on the left.'

'Do ordinary soldiers carry them differently?'

'Correct.'

'Why?'

'Keeps the scabbard out of the way of the shield.' To a foot-soldier unimpeded freedom of movement could mean life or death, but such details failed to interest Xanthus.

'You know, it could have been us!' he trilled enthusiastically. 'If you and I, Falco, had set out earlier than they did this morning, we could have had that chance meeting with the thieves.'

I said nothing. He assumed I was unnerved by the suggestion, so he rode on looking superior. It was another of his irritating habits; he could reason himself halfway through a problem, then his brain stuck.

Even if he and I had ridden out at dawn with clinking saddlebags marked 'Help yourselves' in three European languages, I did not believe that whoever killed the pair would have touched us. This was no straightforward highway robbery. There were oddities here which both Helvetius and I had spotted. For one thing, the two men from Lugdunum had not died that morning. The bodies were cold, and the condition of their clothing showed that they had been lying in the ditch all night. Who travels by night? Not even imperial despatch-riders, unless an emperor has died or they have details of a very lurid scandal involving people at the top. In any case, I had seen the victims at their supper. They had looked unhappy, but had given no impression of needing to dash on with lanterns. They had been resting as leisurely as the rest of us at the tavern that night.

No. Somebody had killed those two men, probably at the village not long after I saw them, then transported the bodies a fair distance in the dark. Perhaps if I had not lingered over my drink, I would have run into the fracas. Perhaps I might even have prevented it. At any rate, after I watched them leave the tavern they must have been sought out, beaten and throttled, then the murders disguised as a natural hazard of travelling so that no questions would be asked.

'All a bit of a coincidence, eh Falco?'

'Possibly.'

Possibly not. But I had no time to stop and investigate. The only question I could ponder as I rode through Cavillonum was, did their sad fate derive entirely from their personal business in Lugdunum-or did it have some bearing on my own task?

I told myself I would never know.

It didn't help.

Argentoratum had forgotten how to welcome strangers-assuming it had ever possessed the knack. The town had hosted a huge army base for as long as Rome had taken an interest in Germany, and its good manners had suffered. This was the original home station of my own legion, the Second Augusta. By the time I had been sent out to them in Britain there had been only a few grumpy veterans with any recollection of life on the Rhine, but Rome's foothold in Britain had always seemed perilous, and in any case, we had always hoped to be posted somewhere better, so Argentoratum had always been a place whose name the men of my legion spoke with a proprietary twang.

That did not mean I could call up old favours when I made the mistake of going there.

I had passed through this hard-faced habitation before, en route to even worse places. At least the last time I had met young Camillus Justinus, who had treated me to a dinner I still remembered plus a tour of the high spots and the low life-which were neither as high as Argentoratum liked to think, nor as low as I was hoping for at the time. I had been depressed-a man in love, though one who had not yet noticed it. I wondered now if Camillus had been able to see that his stately sister (whom I was supposed to be escorting, though as usual Helena had placed herself in charge) had been busy caging me like some little pet singing finch. I looked forward to asking him, and sharing the joke. But I would have to find him first.

Big military centres have their drawbacks. At the fort you can never encounter any sentry you recognise. No friendly official from your last visit has ever stayed in post. The town is equally unpromising. The locals are too busy making money out of the soldiery to bother with casual visitors. The men are brusque and the women contemptuous. The dogs bark and the donkeys bite.

Eventually I dragged Xanthus to the front of a complaining queue at the main guardhouse. I could have registered as an imperial envoy and been poked into a billet inside the fort, but I spared myself a night of being polite to the commissariat. One of the men on guard told me all the bad news I needed to winkle out: they had no listing for the arrival here of any noble tribune's noble sister, and his honour Camillus Justinus had left Argentoratum anyway.

'His replacement came two weeks ago. Justinus had completed his tour.'

'What-gone home to Rome?'

'Hah! This is the Rhine; no one gets to escape that easily! Posted on.'

'Where's he stationed now?'

'No idea. All I know is we get the password for the night watch from some beardless little idiot fresh out of philosophy school. Last night's little gem was xenophobia. Today there are three sentinels in the cells for forgetting it, and a centurion's optio is striding round like a bear who just sat on a thorn-bush because he has to do disciplinary reports on his best tent party.'

No legion in Germany at present could risk mistakes by the guard. The province was under strict martial law-for very good reasons-and there was no room for idiotic tribunes who wanted to show off.

'I imagine your clever new boy is listening to a rich lecture from the legate!' I fought back my worries about Helena, concentrating on her brother. 'Maybe Camillus Justinus was deputed to one of the task-force legions?'

'Want me to make enquiries?' The gateman gave every impression he was prepared to help a tribune's friend, but we both knew he did not intend to leave his stool.

'Don't trouble yourself,' I answered with a courteous sneer. It was time to go. I was all too aware that the barber, who had been peering over my shoulder in a haze of exotic skin lotion, was starting to make a poor impression on this hard-nosed front-line legionary.

I made one last play for information. 'What's the word on the Fourteenth Gemina?'

'Bastards!' retorted the guard.

This unsophisticated parley was all I could expect. In a legionary gatehouse on a dark, wet October night, there was not much scope for light salon conversation. Behind me, two exhausted despatch-riders were waiting to register, Xanthus was looking even more indiscreet, and a very drunk venison-supplier who wanted to dispute a bill with the centurions' dining club was jostling me so closely that I left, not wanting a fight right then, yet feeling as bruised and indignant as a barmaid at a Saturnalia feast.

I booked us into a civilian lodging-house between the fort and the river, so we could make a quick departure at first light. We went to the baths but were already too late for the hot water. Dazed by the way foreign towns draw their shutters so early, we ate a grim supper, forcing it down with acidic white wine, and were then kept awake most of the night by tramping boots. I had settled us in a street full of brothels. Xanthus became intrigued, but I told him the disturbance was just troops on a night exercise.

'Listen, Xanthus. When I go up to Moguntiacum, you can stay here if you like. I'll pick you up for the trip home when I've done what I have to for the Emperor.'

'Oh no. I've come this far, I'll stick with you!'

He spoke as if he was doing me a gigantic favour. I closed my eyes wearily and made no reply.

Next morning I tried to hitch us a ride for nothing, but no luck. The trip down the Rhenus is a highly picturesque one, so the owners of the river barges were charging equally highly for the privilege of surveying a hundred miles of its scenery.