Ours was a wineship; most of them are. We shared the slowly passing vistas with two old fellows and a pedlar. The grandads had bent backs, bald heads, and a series of mouth-watering picnics which they had no intention of sharing round. They sat opposite each other for the whole journey, talking hard, like people who have known one another for a very long time.

The pedlar, who came aboard at a small settlement called Borbetomagus was bent too, but under the trappings of a fold-up stall and the ghastly stuff he sold. Xanthus and I were a captive audience so he soon unknotted the corners of his cloth bundles and spread his offerings on the deck. I ignored him. Xanthus immediately throbbed with crass excitement.

'Look at this, Falco!'

Since I did sometimes make a feeble attempt to save him from his stupidity, I glanced at the trash he was about to invest in now. Then I groaned. This time it was militaria. You may suppose our footslogging heroes would have had enough of kit and harness without spending their pay on more, but never believe it; this canny pedlar was doing a fine trade flogging the legionaries his sad souvenirs of ancient wars. I had seen it in Britain. I had seen it in the cartload of junk my elder brother, who had no sense of proportion, had dragged home from the exotic souks of Caesaria. Here, with nine legions along the Rhenus, most of them bored and all of them flush with imperial silver, there must be a vast scope for trading in quaint tribal buckles, worn-out weaponry and odd jags of iron that could have come off any farm implement.

The man was a native Ubian, all top lip and small talk. The lip was stretched over big buck teeth; the chat was his softening-up technique. It worked on Xanthus. Most things did. I let the two of them get on with it.

The pedlar's name was Dubnus. He was selling the usual native helmets with spikes over the ears, several bowls of 'old' arrowheads and speartips (which he had obviously gathered up last Thursday from a rubbish tip at a previous fort), a dirty drinking-cup which he swore to Xanthus was an aurochs' horn, some links of 'Sarmatian armour', half a set of 'Icenean horse-trappings', and just by the way, a collection of Baltic amber.

None of it contained fossilised insect life, but the amber was the only stuff worth considering. Naturally Xanthus passed straight on without a second glance. I said I would have bought some beads for my girlfriend if they had been matched and threaded properly. Not entirely to my surprise, Dubnus immediately produced from his unsavoury pocket three or four decent necklace strands-at three or four times the price.

We spent a tolerable half-hour haggling over the string with the smallest beads. I beat him down to about a quarter of the asking price just for the vocal exercise, then snapped up one of the better necklaces as I had intended all along. The pedlar had weighed me up cannily, but Xanthus looked startled. He did not know I had spent my childhood burrowing around the Saepta Julia second-hand stalls. I also thought it might be wise to buy a present for Helena's birthday in case I ran into her. I was missing her. It made me an easy mark for anyone hawking trinkets that showed slight vestiges of taste.

Judging that my purse was now firmly closed, Dubnus turned his whining charm on Xanthus again. He was an artist. As an auctioneer's son, I almost enjoyed watching it. Luckily, we were not sailing all the way down to the delta, or the barber would have bought up the pedlar's entire stock. He did fall for the aurochs' horn, supposedly hacked by Dubnus himself from one of the wild Gallic oxen whose savage temper is legendary:

'I'd really like to see one of those, Falco!

'Just be thankful it's unlikely!'

'You ever spied one on your travels?'

'No. I'm sensible, Xanthus-I never wanted to.'

His acquisition was a fairly useful drinking-cup, which didn't spill too much down his tunic neck when he attempted to use it. He managed to polish it up to a handsome shine. I never told him that aurochs don't have twisted horns.

As the wineship floated on to our destination, Dubnus slowly rewrapped his treasures. Xanthus began to handle a helmet. Partly to rescue him before he was bankrupt (because that would mean I'd have to pay for everything), I took the item away from him.

It looked like army issue at first, but with differences. The modern helmet incorporates a deeper guard around the back, protecting the neck and shoulders; it also has cheekpieces and extra protection over the ears. I suspect the revised design was developed to counter damage from Celtic broadsword swipes. The original pattern had been superseded long before my time, but I was staring at one now.

'This must be quite an antique, Dubnus.'

'I call that a relic of the Varus disaster!' he confessed amiably, as if owning to a fake; then his eyes met mine and he had second thoughts. I managed to stop myself shivering.

'Where did you get it?'

'Oh: somewhere in the woods.' His voice faded evasively.

' Where?' I asked again.

'Oh: up in the north.'

'Somewhere like the Teutoburger forest?'

He was reluctant to clarify. I dropped to one knee, surveying his stock more attentively. He had marked me up as trouble, so he didn't like me doing it. I ignored his agitation. That worried him even more.

Now I noticed a piece of old bronze that could have come from a Roman sword pommel; clasps that resembled a set I had seen at my grandfather's house; a holder for a helmet plume-another discontinued line, now altered to a carrying loop.

'Sell a lot of these "Varus relics", do you?'

'People believe what they want to.'

There was also a blackened object I refused to handle because I guessed it was a human skull.

I stood up again.

Augustus's stepgrandson, the heroic Germanicus, was supposed to have found where the massacre had taken place, collected the scattered remains of the dead, and given the lost army of Varus some kind of decent funeral-but who believes that out in the hostile forest Germanicus and his nervous troops spent too much time offering themselves as another target? They did their best. They brought the lost standards back to Rome. After that we could all sleep with clear consciences. It was best not to think that somewhere deep in the dark woods of unconquered Germany broken weapons and other booty might still lie among unburied Roman bones.

The troops of today would buy this mouldy paraphernalia. Army lads love souvenirs that smack of manly deeds in dangerous venues. The grislier the better. If Dubnus really had discovered the old battle site, he must be coining it.

I avoided the issue by probing for my own purposes. 'So you go across the river, do you? In the north?' He shrugged. Commerce breeds daring. In any case, free Germany had never been a no-go area for the purposes of trade. 'How far do your travels take you? Ever come across the famous prophetess?'

'Which prophetess would that be?'

He was teasing. I tried not to look particularly interested, in case word of my mission ran ahead of me. 'Is there more than one sinister spinster wielding influence over the tribes? I mean the bloodthirsty priestess of the Bructeri.'

'Oh, Veleda!' sneered Dubnus.

'Ever met her?'

'No one meets her.'

'Why's that?'

'She lives at the top of a high tower in a lonely place in the forest. She never sees anyone.'

'Since when have prophets been so shy?' Just my luck. A really weird one. 'I never imagined she kept a marble office, with an appointments secretary serving peppermint tea for visitors, but how does she communicate?'

'Her male relations carry messages.' Judging by the effect Veleda had had on international events, her uncles and brothers must have busily trampled a wide swathe through the woods. It rather took the shine off her elusiveness.