‘Darling, I’m awfully sorry. We tried to get back but I twisted my heel — ‘ Louise Gifford laughed lightly at this ‘rather as you did, now that I come to think of it. Perhaps I’ll be joining you here in a day or two. I’m so glad Mechippe looked after you and changed the dressing. How do you feel? You look a lot better.’

Gifford nodded drowsily. The afternoon fever had subsided but he felt drained and exhausted, his awareness of his wife’s chattering presence only stimulated by the whisky he had been drinking slowly all day. ‘It’s been a day at the zoo,’ he said, adding, with tired humour: ‘At the reptile enclosure.’

‘You and your snakes. Charles, you are a scream.’ Louise paced around the stretcher-chair, downwind of the cradle, then withdrew to the lee-side. She waved to Richard Lowry, who was carrying some specimen trays into his tent. ‘Dick, I suggest we shower and then join Charles for drinks.’

‘Great idea,’ Lowry called back. ‘How is he?’

‘Much better.’ To Gifford she said: ‘You don’t mind, Charles? It will do you good to talk a little.’

Gifford gestured vaguely with his head. When his wife had gone to her tent he focused his eyes carefully on the beaches. There, in the evening light, the snakes festered and writhed, their long forms gliding in and out of each other, the whole darkening horizon locked together by their serpentine embrace. There were now literally tens of thousands of them, reaching beyond the margins of the beach across the open ground towards the camp. During the afternoon, at the height of his fever, he had tried to call to them, but his voice had been too weak.

Later, over their cocktails, Richard Lowry asked: ‘How do you feel, sir?’ When Gifford made no reply he said: ‘I’m glad to hear the leg is better.’

‘You know, Dick, I think it’s psychological,’ Louise remarked. ‘As soon as you and I are out of the way Charles improves.’ Her eyes caught Richard Lowry’s and held them.

Lowry played with his glass, a faintly self-assured smile on his bland face. ‘What about the messenger? Is there any news?’

‘Have you heard anything, Charles? Perhaps someone will fly over in a couple of days.’

During this exchange of pleasantries, and those which followed on the subsequent days, Charles Gifford remained silent and withdrawn, sinking more deeply into the interior landscape emerging from the beaches of the delta. His wife and Richard Lowry sat with him in the evenings when they returned from the terrace city, but he was barely aware of their presence. By now they seemed to move in a peripheral world, players in a marginal melodrama. Now and then he would think about them, but the effort seemed to lack point. His wife’s involvement with Lowry left him unperturbed; if anything, he felt grateful to Lowry for freeing him from Louise.

Once, two or three days later, when Lowry came to sit by him in the evening, Gifford roused himself and said dryly: ‘I hear you found treasure in the terrace city.’ But before Lowry could produce a reply he relapsed again into his vigil.

One night shortly afterwards, when he was woken in the early hours of the morning by a sudden spasm of pain in his foot, he saw his wife and Lowry walking through the powdery blue darkness by the latter’s tent. For a fleeting moment their embracing figures were like the snakes coiled together on the beaches.

‘Mechippe!’

‘Doctor?’

‘Mechippe!’

‘I am here, sir.’

‘Tonight, Mechippe,’ Gifford told him, ‘you sleep in my tent. Understand? I want you near me. Use my bed, if you want. Will you hear if I call?’

‘Of course, sir. I hear you.’ The head-boy’s polished ebony face regarded Gifford circumspectly. He now tended Gifford with a care that indicated that the latter, however much a novice, had at last entered the world of absolute values, composed of the delta and the snakes, the brooding presence of the Toltec ruin and his dying leg.

After midnight, Gifford lay quietly in the stretcher-chair, watching the full moon rise over the luminous beaches. Like a Medusa’s crown, thousands of the snakes had climbed the crests of the beaches and were spreading thickly across the margins of the plain, their white backs exposed to the moonlight.

‘Mechippe.’

The head-boy had been squatting silently in the shadows. ‘Dr Gifford?’

Gifford spoke in a low but clear voice. ‘Crutches. Over there.’ As the head-boy passed the two carved sticks Gifford tossed aside the blankets. Carefully he withdrew his leg from the cradle, then sat up and lifted it on to the ground. He leaned forward into the crutches and found his balance. The bandaged foot, like a white club, stuck out in front of him. ‘Now. In the field-desk, right-hand drawer, there’s my gun. Bring it to me.’

For once the head-boy hesitated. ‘Gun, sir?’

‘Smith & Wesson. It should be loaded, but there’s a box of cartridges.’

Again the head-boy hesitated, his eyes roving to the two tents spaced in a line away from them, their entrances hooded by the dust canopies. The whole camp lay in silence, the light stirring of the wind muted by the still warm sand and the dark talcum-like air. ‘Gun,’ he said. ‘Yes, sir.’

Easing himself slowly to his feet, Gifford paused uncertainly. His head swam with the exertion, but the huge anchor of his left foot held him to the ground. Taking the pistol, he gestured with it towards the delta.

‘We’re going to see the snakes, Mechippe. You help me. All right?’

Mechippe’s eyes flashed in the moonlight. ‘The snakes, sir?’

‘Yes. You take me halfway there. Then you can come back. Don’t worry, I’ll be all right.’

Mechippe nodded slowly, his eyes looking out over the delta. ‘I help you, doctor.’

Labouring slowly across the sand, Gifford steadied himself on the head-boy’s arm. After a few steps he found his left leg too heavy to lift, and dragged the dead load through the soft sand.

‘Christ, it’s a long way.’ They had covered twenty yards. By some optical freak the nearest snakes now seemed to be half a mile away, barely visible between the slight rises. ‘Let’s get on with it.’

They plodded on a further ten yards. The open mouth of Lowry’s tent was on their left, the white bell of the mosquito net looming in the shadows like a sepulchre. Almost exhausted, Gifford tottered unsteadily, trying to focus his eyes through the tinted air.

There was a sudden flash and roar as the revolver discharged itself, cannoning out of his hand. He felt Mechippe’s fingers stiffen on his arm, and heard someone emerge from Lowry’s tent, a woman’s startled cry of fear. A second figure, this time a man’s, appeared and with a backward glance at Gifford darted away like a startled animal among the tents, racing head down towards the terrace city.

Annoyed by these interruptions, Gifford searched blindly for the revolver, struggling with the crutches. But the darkness condensed around him, and the sand came upwards to strike his face.

The next morning, as the tents were dismantled and packed away, Gifford felt too tired to look out across the delta. The snakes never appeared until the early afternoon, and the disappointment of failing to reach them the previous night had drained his energy.

When only his own tent remained of the camp, and the naked shower scaffoldings protruded from the ground like pieces of abstract sculpture marking a futuristic cairn, Louise came over to him.

‘It’s time for them to pack your tent.’ Her tone was matter-of-fact but guarded. ‘The boys are building a stretcher for you. You should be comfortable.’

Gifford gestured her away. ‘I can’t go. Leave Mechippe with me and take the others.’

‘Charles, be practical for once.’ Louise stood before him, her face composed. ‘We can’t stay here indefinitely, and you need treatment. It’s obvious now that Mechippe’s boy never reached Taxcol. Our supplies won’t last for ever.’