'Anyway, was it really an oversight?' Helena asked some time later – a girl not easily deflected. If she was thinking that letting me kiss her had softened me up, she was right.

'Forgetting to mention Anacrites? Certainly. I don't lie to you.'

'Men always say that.'

'Sounds as if you've been talking to Thalia. I can't be held responsible for all the other lying bastards.'

'And usually you say it in the middle of an argument.'

'So you reckon it's just the line I use? Wrong, lady! But even if that were true, we do need to preserve a few escape routes! I want us to survive together,' I told her piously. (Frank talk always disarmed Helena, since she expected me to be devious.) 'Don't you?'

'Yes,' she said. Helena never messed me around playing coy. I could tell her that I loved her without feeling embarrassed, and I knew I could rely on her to be equally frank: she thought I was unreliable. Despite that she added, 'A girl doesn't come this far across the world with a mere Thursday-afternoon dalliance!'

I kissed her again. 'Thursday afternoons? Is that when senators' wives and daughters have free run of the gladiators' barracks?' Helena wriggled furiously, which might have led to more playfulness had our baking rock seat not lain right alongside a well-beaten track. A stone fell somewhere. We both remembered the voices we had heard, and were afraid their owners might be coming back. I did wonder if I could take us off up the hillside, but its steepness and stoniness looked unpromising.

I loved travelling with Helena – except for the frustrating series of small cabins and cramped hired rooms where we never felt free to make love. Suddenly I was longing for our sixth-floor tenement apartment, where few interlopers struggled up the stairs and only rooftop pigeons overhear.

'Let's go home!'

'What – to our rented room?'

'To Rome.'

'Don't be silly,' scoffed Helena. 'We're going up to see the mountaintop.'

My only interest in the mountaintop had been the possibilities it offered for grappling Helena. Nevertheless I put on my serious traveller's face and we continued uphill.

The summit was announced by a pair of unequal obelisks. Perhaps they represented gods. If so, they were crude, mysterious, and definitely alien to the human-featured Roman pantheon. They appeared to have been created not by transporting stones here, but by carving away the entire surrounding rock-bed to a depth of six or seven metres to leave these dramatic sentinels. The effort involved was staggering, and the final effect eerie. They were unidentical twins, one slightly taller, one flared at the base. Beyond lay some sort of strongly built building that we preferred not to investigate in case it was occupied by priests honing sacrificial knives.

We climbed on, reaching the ceremonial area by a steep flight of steps. This brought us out on to a windswept promontory. On all sides the high, airy rock offered staggering views of the circlet of harsh mountains within which Petra lies. We had emerged on the north side of a slightly sunken rectangular court. Around it had been cut three benches, presumably for spectators, like the triple couches in a formal dining room. Ahead of us lay a raised platform on which were displayed offerings that we tactfully ignored. To the right, steps led to the main altar. There a tall column of black stone represented the god. Beyond him lay another, larger, round altar like a basin cut from the living rock, connected by a channel to a rectangular water tank.

By now my imagination was working at a hairy pace. I hoped I was impervious to awe-striking locations and sinister religions, but I had been to Britain, Gaul and Germany; I knew more than I wanted about unpleasant pagan rites. I grasped Helena's hand as the wind buffeted us. She walked fearlessly out on to the sunken court, gazing at the spectacular views as if we were on some balustraded vista provided for the convenience of summer tourists above the Bay of Surrentum.

I was wishing we were. This place gave me a bad feeling. It aroused no sense of reverence. I hate ancient sites where creatures have long been slain for the grim delight of monolithic gods. I especially hate them when the local populace like to pretend, as the Nabataeans did with great relish, that some of the creatures they sacrificed could have been human. Even at that point I felt alert, as if we were walking into trouble.

There was trouble at Dushara's shrine all right, though it did not yet directly involve us. We still had time to avoid it -though not for much longer.

'Well, this is it, my darling. Let's go back now.'

But Helena had spied some new feature. She pushed her hair back out of her eyes and dragged me over to look. To the south of the ceremonial area lay another rectangular reservoir. This one apparently drained the summit to provide an ample supply of fresh water for the rites of sacrifice. Unlike the rest of the High Place, this cistern was occupied.

The man in the water could have been taking a swim in the sunlight. But as soon as I spotted him I knew that he was not floating there for pleasure or exercise.

If I had had any sense I would still have convinced myself he was just bathing peacefully. We could have turned away without staring too closely, then a rapid stroll downhill would have taken us back to our lodging. We should have done that anyway; I should have kept us out of it.

He was almost submerged. His head was under water. Only something bulky, caught under his clothing, was holding him afloat.

We were both already running forwards. 'Unbelievable!' Helena marvelled bitterly as she scrambled down from the sacrificial platform. 'Just two days here, and look what you've found.'

I had reached the rock-formed tank ahead of her. I lowered myself over the edge into the water, trying to forget I couldn't swim. The water came above my waist. The chill made me gasp. It was a large cistern, about four feet deep: ample to drown in.

The swirl of water as I entered caused the body to move and start sinking. I managed to grab at the garments that had helped buoy him up. Arriving a few moments later, we could have avoided this trouble. He would have been lying out of sight on the bottom as the drowned do – assuming, of course, that drowning was the real cause of his death.

Slowly I pulled my burden to the side. An inflated goatskin floated out from under his tangled cloak as I manoeuvred him. Helena leant down and held his feet, then helped me haul him half out of the water. She had the nice manners of any senator's daughter, but no qualms about helping out in an emergency.

I climbed out again. We completed the operation. He was heavy, but together we managed to remove him from the cistern and flop him face down. Without more ado I turned his head sideways. I leaned on his ribs for a respectable period, trying to revive him. I noticed my first shove seemed to expel air rather than water. And there was none of the froth I had seen with other corpses who had drowned. We get plenty in the Tiber.

Helena waited, at first standing above me with the wind blowing her clothes against her body while she gazed thoughtfully around the high plateau. Then she walked to the far side of the cistern, examining the ground.

As I worked I was thinking things through. Helena and I had been climbing quite slowly, and our pause for recreation had taken up time. But for that, we would have arrived at the crucial moment. But for that, we would be sharing the fabulous windswept views with two men, both alive.

We had come too late for this one. I knew even before I started that my efforts would be useless. Still, I gave him the courtesy. I might need to be resuscitated by a stranger myself one day.