So Paul Biedermann had taken flight despite the appointment I'd made with him. I was not surprised. There had always been a streak of cowardice in him.

I had no difficulty getting inside the house. The front door was locked but a ladder left on the grass reached to one of the balconies. The sliding window, secured only by a plastic clip, was easy enough to force.

There was still enough daylight coming through the window for me to see that the master bedroom had been tidied and cleaned with that rigorous care that is the sign of leave-taking. The huge double bed was stripped of linen and covered with clear plastic covers. Two small carpets were rolled up and sealed into bags that would protect them from termites. Torn up and in the waste-paper basket I found half a dozen Mexico City airport luggage tags dating from some previous journey, and three new and unused airline shoulder-bags not required for the next. The sort of airline bags that come free with airline tickets were not something that the Biedermanns let their servants carry. I stood listening, but the house was completely silent. There was only the sound of the big Pacific Ocean waves battering against the rocks below the house and roaring their displeasure.

I opened one of the wardrobes. It smelled of moth repellent. There were clothes there: a man's cream-coloured linen suits, brightly coloured pants and sweaters, handmade shoes – treed and in shoe-bags embroidered 'P.B.' – and drawers filled with shirts and underclothes.

In the other wardrobe, a woman's dresses, expensive lingerie folded into tissue paper and a multitude of shoes of every type and colour. On the dressing table there was a photo of Mr and Mrs Biedermann in swimsuits standing on a diving board and smiling self-consciously. It had been taken before the car accident.

The three guest bedrooms on the top floor – each with separate balcony overlooking the ocean and private bathroom – had all been stripped bare. Inside the house, a gallery that gave access to the bedrooms was open on one side to overlook the big lounge downstairs. All the furniture was covered in dustsheets, and to one side of the lounge there was a bucket of dirty water, a trowel, some adhesive and dirty rags marking a place where a large section of flooring was being retiled.

Only when I got to Biedermann's study, built to provide a view of the whole coastline, was there any sign of recent occupancy. It was an office; or, more exactly, it was a room furnished with that special sort of luxury furniture that can be tax-deducted as office equipment. There was a big puffy armchair, a drinks cabinet, and a magnificent wood-inlay desk. In the corner there was that sort of daybed that Hollywood calls a 'casting couch'. On it there were blankets roughly folded and a soiled pillow. A big waste-bin contained computer printout and some copies of the Wall Street Journal. More confidential print-out was now a tangle of paper worms in the clear plastic bag of the shredder. But the notepads were blank, and the expensive desk diary – the flowers of South America, one for every week of the year in full colour, printed in Rio de Janeiro – never used. There were no books apart from business reference books and phone and telex directories. Paul Biedermann had never been much of a reader at school but he'd always been good at counting.

I tried the electric light but it did not work. A house built out here on the edge of nowhere would be dependent upon a generator operating only when the house was occupied. By the time I had searched the house and found no one, the daylight was going fast. The sea had turned the darkest of purples and the western skyline had almost vanished.

I went back up to the top floor and chose the last guest room along the gallery as a place to spend the night. I found a blanket in the wardrobe and, choosing one of the plastic-covered beds, I covered myself against the cold mist that rolled in off the sea. It soon became too dark to read and, as my interest in the Wall Street Journal waned, I drifted off to sleep, lulled by the sound of the waves.

It was 2.35 when I was awakened by the car. I saw its lights flashing over the ceiling long before I heard its engine. At first I thought it was just a disturbed dream, but then the bright patch of light flashed across the ceiling again and I heard the diesel engine. It never struck me that it might be Paul Biedermann or any of the family coming home. I knew instinctively that there was danger.

I slid open the glass door and went outside on to the balcony. The weather had become stormy. Thin ragged clouds raced across the moon, and the wind had risen so that its roar was confused with the sound of the breakers on the rocks below. I watched the car. The headlights were high and close together, a configuration that suggested some jeep-like vehicle, as did the way it negotiated the bad road. It was still going at speed as it swung round the back to the garage area. The driver had been here before.

There were two voices; one of the men had a key to the front door. I went through the guest bedroom and crouched on the interior gallery so that I could hear them speaking in the lounge below.

'He's run away,' said one voice.

'Perhaps,' said the other, as if he didn't care. They were speaking in German. There was no mistaking the Berlin accent of Erich Stinnes, but the other man's German had a strong Russian accent.

'His car is not here,' said the first man. 'What if the Englishmen arrived before us and took him off with them?'

'We would have passed them on the road,' said Stinnes. He was perfectly calm. I heard the sound of him putting his weight on to the big sofa. 'That's better.' A sigh. 'Take a drink if you want it. It's in the cabinet in his study.'

'That stinking jungle road. I could do with a bath.'

'You call that jungle?' said Stinnes mildly. 'Wait till you go over to the east coast. Wait until you go across to the training camp where the freedom fighters are trained, and cut your way through some real tropical rain forest with a machete, and spend half the night digging chiggers out of your backside. You'll find out what a jungle is like.'

'What we came through will do for me,' said the first man.

I raised my head over the edge of the gallery until I could see them. They were standing in the moonlight by the tall window. They were wearing dark suits and white shirts and trying to look like Mexican businessmen. Stinnes was about forty years old: my age. He had shaved off the little Lenin-style beard he'd had when I last saw him but there was no mistaking his accent or the hard eyes glittering behind the circular gold-rimmed spectacles.

The other man was much older, fifty at least. But he was not frail. He had shoulders like a wrestler, cropped head and the restless energy of the athlete. He looked at his watch and then out of the window and then walked over to the place where the tiles were being repaired. He kicked the trowel so that it went skidding across the floor and hit the wall with a loud noise.

'I told you to have a drink,' said Stinnes. He did not defer to the other man.

'I said you should frighten Biedermann. Well, you've frightened him all right. It looks as if you've frightened him so much that he's cleared out of here. That's not what they wanted you to do.'

'I didn't frighten him at all,' said Stinnes calmly. 'I didn't take your advice. He's already too frightened. He needs reassurance. But he'll surface sooner or later.'

'Sooner or later,' repeated the elder man. 'You mean he'll surface after you've gone back to Europe and be someone else's problem. If it was left to me, I'd make Biedermann a number-one priority. I'd alert every last KGB team in Central America. I'd teach him that an order is an order.'

'Yes, I know,' said Stinnes. 'It's all so easy for you people who sit at desks all your life. But Biedermann is just one small part of a complicated plan… and neither of us knows exactly what the plan is.'