'I'll watch out for them,' I said.

'Do that,' said the boy. The rocks here were volcanic, teeth riddled with cavities so that the sea gurgled and gulped and vented spray that hissed before falling back, in a flash of fluorescent light, on to the sharp, black molars.

'Thanks for the cigarettes,' the girl said very quietly as we moved away. There was another girl alongside her. She put her arm round the girl who'd been crying and, as we moved away, she said, 'Try and go to sleep, Betty. Tomorrow we must move on.'

Werner and I strolled back along the beach and then got into the little pick-up truck. It had four-wheel drive and had managed the final section of road without much trouble. Werner had borrowed it. He had an amazing ability to get almost anything at any time anywhere. I didn't ask where it had come from. He looked at his watch. 'Stinnes should be here any minute,' he said.

'A man like that is usually early,' I said.

'If you've got any doubts…'

'No, we'll hang on.'

'Did you wonder who those people were on the beach? Did you guess they were hippies?'

'I'm still wondering,' I said. I could taste the salt spray on my lips and I polished my glasses again to get rid of the marks.

'What the girl was crying about? Is that what you're wondering?'

'Six people back-packing through miles of scrub but there's seven packs?'

'One belongs to the kid who went looking for the clinic. Hell, you know the crazy things people do.'

'An injured kid abandons his back-pack? That's like saying he's abandoned all his belongings.'

'It's possible,' said Werner.

'And the other six carry an extra back-pack? How do you do that, Werner? Never mind cutting your way through the scrub at the same time. How do you carry a back-pack when you're already wearing one? Try it some time.'

'So what are you saying?'

'If those kids had an extra pack to carry they would take it to pieces and distribute it. More likely – seeing those kids – they would sell it in the local village where a decent pack would get them some stores or something to smoke or whatever they wanted.'

'And the boy had a bad cut on his arm,' said Werner.

'A bad cut in exactly the right place, Werner, the left forearm. And there were cuts on his hand too. Maybe more cuts under the borrowed T-shirt. The girl was sobbing like her heart was broken. And the other girl was comforting her.'

'Someone had taken a shower bath.'

'Yes, and washed one set of clothes,' I said. 'Four men and three girls, sleeping on the beach each night. It's a recipe for trouble.'

'Why dig for water? There must be water in the village,' said Werner.

'Sure. And you can bet that Biedermann didn't start building his house until he found water there.'

'If we're guessing right, we should tell the police,' said Werner.

'Oh, sure,' I said. 'That's all we need, the local cops quizzing us all night and walking all over Stinnes and Biedermann too. I can't think of any surer way of ending any chance of enrolling Stinnes than having him walk into a murder investigation that we've made sure coincided exactly with his expected time of arrival.'

'I don't like the idea of just doing nothing about it,' said Werner.

'Sometimes, Werner, you amaze me.'

He didn't answer. I'd seen him like this before. Werner was in a self-righteous sulk. He thought I should report my suspicions to the police and I had no doubt that he was preparing a lecture to which I would be subjected when he had it word-perfect. We sat in the car, watching the eastern sky lighten and thinking our own thoughts, until, half an hour later, we saw the headlights of two cars bumping along the track towards us.

Stinnes was in one car and Paul Biedermann in the other. One of the cars had got stuck on the final stretch of bad road. Biedermann opened the gate without more than a mumbled greeting and we all drove up to the house.

'I'm sorry about the locked gate,' said Biedermann. There had been no formal introductions. It was as if by tacit consent this was to be a meeting that never took place. The servants must have forgotten what I told them.'

The 'servants' were a man and boy who, judging by the state of their boots, had recently arrived by the footpath that I had taken on the previous visit. They gave us mugs of the very sweet coffee made from the sugar-coated coffee beans that Mexicans like. They wore checked shirts and jeans. One of them was little more than a child. I guessed they were also the 'crew' of Biedermann's motor boat. They treated Biedermann with a surly deference that might have been the result of the drunken rages that he was reputed to indulge in. But now Biedermann was sober and withdrawn. The four of us stood on the patio looking at the sun-streaked dawn sky and down to where a forty-foot cabin cruiser was at anchor a hundred metres offshore.

I took this opportunity to look at Stinnes, and I suppose he was making the most of this chance to study me. It was only his perfect German and the Berlin accent that made it possible for Stinnes to be mistaken for a native Berliner. Such thin, wiry bodies and Slavic faces are common on the streets of Moscow. He'd removed his straw hat and revealed a tall forehead and hair that was thinning enough to show the shape of his skull. His eyes flittered behind small, circular, gold-rimmed spectacles that now he took off to polish while he looked around. He'd been in the sun, and the chin from which he'd shaved a small beard was darkened. But his complexion was sallow and without pigment enough to tan evenly. In the Mexican sun his cheekbones and nose had turned a yellowish brown like the nicotine-stained fingers of a heavy smoker. And his cotton suit – so light in colour as to be almost white – was ill fitting and wrinkled by the car journey. And yet, for all that, Stinnes had the quick intelligent eyes and tough self-confidence that makes a man attractive to his fellow humans.

'Let's get going,' said Biedermann impatiently. He was nervous. He made sure he never met my gaze. 'Leave the coffee. Pedro and his son will make more on the boat if you want it. We're taking food with us.' He fussed about us like a tour guide, leading the way as we went down to the pier. He was telling us to mind the steps and to watch out for the mud or the slippery wooden boards. I looked along the coast to see the hippies on the beach, but it was too far and they were hidden by the rocks. I looked back over my shoulder. Stinnes was at the very rear, picking his way down the steps with exaggerated care, his straw hat, old-fashioned spectacles and creased white suit making him look like a character from Chekhov. Not the muddled, avuncular Chekhov of the Western stage but the cold, arid class enemy that the Soviet theatre depicts.

The sun was coming through the haze now, its yellowish glare like a melted blob of butter oozing through a tissue-paper wrapping. No one had commented on Werner's presence, and I was grateful to him for being there. Either they didn't plan to get rough, or they planned to get so rough that one extra victim would make no difference.

It was named Maelstrom and was the sort of boat that the Paul Biedermanns of this world love. It stood high out of the water with a top deck used for spotting and an awning-covered stern and a big 'dentist's chair' for the man who was fishing. The lounge was lined with expensive veneering and had a stereo hi-fi, a big TV and a wet bar with refrigerator. Steps up from there gave on to a big 'bridge' where a swivel seat provided the captain with a panoramic view through the wrap-around windscreen. There was even a yachting cap with the word 'captain' entwined in crossed anchors and embroidered in fine gold wire. But Pedro the Mexican didn't wear the captain's hat; his long greasy hair would have stained it. He sat at the controls like a long-distance bus driver waiting at a depot. He rested on the wheel, toying with a wrapped cheroot that he never lit. There was a cheap transistor radio jammed behind the sun visor. He tuned it to a local station that played only Mexican music, and then turned the volume down so that it couldn't be heard in the lounge.