We really would be better off without them, he thought; as a breed. Apart from all the fuss. And it saddened him that a woman's needs should be so monstrously met, if not by her lovers then by her sons. That Eve should kiss not just Adam but also Cain. That it all keeps trundling on. It leaves her, and then it comes back to her again.

As he fell asleep, he heard her talking to the boy, through the wall.

Tancho,' she said. 'Where did we get this thing?'

Ί think we got it in the cathedral in Asuncion’

'Well it is a very ugly thing’

And Stewart spent his dreams wondering what the thing might be.

The next evening, Stewart sought out the boy again. He could not help it. He wanted to talk to the future. He wanted to see those eyes.

'For all her nonsense, you know, mine is an important position. If we lose her we are absolutely lost’

'Yes,' said Stewart.

Although it was the boy he believed in now, and not the mother. The boy's mother was a whore. It was never a word that made sense to Stewart, but it made sense to him now. It was the prickle on his skin of hatred or disgust – the unbearable tenderness where his skin met the night sky. The sensation of falling. Stewart thought that he might fly apart with it. It was a rage and a yearning, and the only word he could put on it was 'whore'. Everything was dirty and dark, now, and his waking dreams stank of Eliza, until he had to seek out her son and rest his eyes on him.

Pancho, as though he sensed his need, tried to put the older man at ease – but of course it was hard for a boy who had been reared as he had been reared to find the right tone. He settled on a story.

Ί bet my boys they would not take the witch Cordai,' he said. 'It was in Humaitá, when she was still caged. Did you see her? If you threw her a bone she would twist it in front of her face like she had never seen a bone before, and my lads were all frightened – she would fling it back at them and they would scatter and shout – or she would gnaw at it, all leering, and once she put it into her private self, whatever you call it, her cunt, though not far. So I knew she was daring us, and I threw a belt buckle I had into the cage for the first man to take the witch Cordai.

'You should have heard my father laugh. He said he would write it in his "Maxims" that a dare is a mirror, because once I said it, of course, I was obliged to enter the cage myself, and attempt the deed. But I did it. Just about – the place being so confined, and the witch, as you may imagine, none too pleased’

Ί can imagine,' said Stewart.

'She bucked so much and spat. I swear it – I saw burn marks on the floor.'

'Really?' said Stewart, who was beginning to hear nothing now.

'She hexed my father, once, you know, but it did not work.'

Thompson's horse died. Stewart sucked its handsome tendons. He chewed them for days at a time. And, once he had eaten the inside of them, he wore the horse's shins pulled up his own legs, with the fetlocks stitched together, for leather socks or hairy boots.

One day, he looked down from the mountains back to the gently folding Cordillera, and noticed that the girl was gone. She had been getting smaller and smaller. It had been hard, for a while, to realise the lack of her. Stewart looked around him, over and again, wondering what was missing – was it his knife? The three bullets he had found to load into his pistol, if the powder ever came his way? When he saw that it was the girl, Stewart's mind went back along the trail looking, not for her, but for the man he had been when he had the girl by his side. Days back. Perhaps a week. When he found him – this past version of Doctor Stewart – he pulled him into himself for a fierce, short embrace.

Yes, the man told him, she was gone. She had been slipping into the bushes more and more often. Her looseness was turning to cholera, even though the air was now so clear. Yes, even when the cholera was leaving them, it was taking her with it. And at night her body had leaked in his easy embrace. And, sometime that morning, she had fallen down and Stewart had not picked her up. And why should he pick her up? There was no time. The Brazilians were hours away. There was no turpentine, nor any emetic to treat her with, and what little he had was kept for the exclusive use of Senor Lopez.

At which, Stewart let his old self go again, and turned back to the black carriage that was creeping like a beetle up the flank of the hill.

By the banks of the Aquidabánmi, the ox that pulled the piano cart died, as did many of the men. They were on the brink of the high meadow lands, where the forest began to thin, a place blessed by hummingbirds and friendly breezes, also circled by the Karakara vulture, who must have known something about the stream there, because three hours after drinking the water they were seized, both animal and human, by griping pains. They could barely pitch camp, and that night you could hear Lopez raving in the darkness, though maybe it was some other man – a strong man – bellowing at death. But despite the roaring, death had taken, as they saw when the morning came, the weakest oxen, and many infants, and considerable numbers of women and men.

Lopez ordered the piano abandoned there, and he had to give the order twice. His own son looked at him, and then jumped to. And when they had it down off the cart, two of his boy brigade folded the huge cloth with that folding dance you see women make, shepherds coming to kiss shepherdesses, over and back, over and across, and over again.

Eliza was in her carriage for this. She did not pretend to watch, but the horses started away just as soon as the piano was left on the grass. Stewart, who stayed to tend the survivors, was left looking at the thing, standing proud in a field full of bodies, silent or groaning. The temptation was too much for him. He lifted the lid and played her out. As the line of fleeing Paraguayans trickled over the far hills, Stewart let his ruined hands wander over the notes. He found he was playing ' La Palomita', as though there was no other tune the piano knew, so he drummed the same note for a while, to admonish it. And when he looked away for long enough – at the beautiful birds, for example, or the beautiful hills – he found an old tune wandering out of his hands. Something Scottish, he thought, although he could not remember the name.

When he caught up with them that night, Lopez was impatient at the delay. His stools were yellow he said. They smelled of smoke. Stewart prescribed charcoal. He said, with a laugh, that at least there was plenty of that about – then realised, as he looked at Lopez, that he had just very nearly died.

But he had not died. He had been given something to eat, and he had lain down. He watched the stars while his back sought and swooned into the hard Paraguayan earth, and he listened, as they all did, to the fight in the presidential tent.

They fought in French. There was an occasional shadow-play of bodies on the canvas, but the figures loomed or receded hopelessly; or ate themselves, as they flicked from one to the other wall. It was hard to tell what was going on. Eliza was keening for her piano, of course. But she would not say it: she wouldn't mention it by name. Instead there was a litany of things she had to put up with: incessant travel and bad food and no help and badly washed clothes. Her throat was so full that she choked on the words, she had to squeeze them out of her, until her voice broke in a thin shriek, a wail.

'And when will we be married, you son of a bitch? When will you marry me?'

By the sound of it, she was up close to him. Stewart imagined that he held her by the wrists. She was trying to hit him, or bite him. Those handsome teeth. Of course, Lopez could take out a pistol and shoot her. He could push her out of the tent and have her lanced before she stumbled to the ground. He could put her in with the prisoners and have her daily flogged. And then – and this was the greatest comfort to them in these last, terrible days – he could do none of these things, because he loved Eliza Lynch.