He did not think of it during the day – there was always some other irritation to occupy his mind; a man's skin that was designed as a penance and not a protection; the changing vista, the clouds hanging in the branches of some forest, the feeling of legend from the landscape, and also of unfairness when you looked at such wide beauty from the narrow torment of your body; a chafed heel, an ulcerated shoulder, or the sense of your life gone astray. And then, around noon, there was the daily despair. It was a physical thing, like a drench of rain; you were dripping with it. It burdened every part and compartment of Stewart with a liquid grief, so that he wasn't so much riding as carrying his tears, brimming in some slopping leather bag, with gaps spouting in the seams.

And with the sadness came a decision. He would put his burden down. Every day, around noon, Stewart resolved to kill himself by the nearest means. He loved the force of the resolution; relished the relief. He craved death as much as water, more than food, and he fingered the handle of his knife at his side.

But he would have to pull away into the trees – and where was the right path among them, the most forgiving glade? The wound would have to be just so. The pistol in his saddlebag lacked shot. He might reach into his saddlebag, or fondle the leather plaiting on the handle of the knife. He might remember to put the leather in his mouth, because the doctor in him knew that this moment would pass, if he would only eat.

And yet, his throat was so dry. He might suck a little on the knife. Or he might nick the inside of his cheek to feel something sharp and taste the blood. Then it would come to him in a rush and he would stuff whatever handful he had been given into his mouth. After a moment, he would feel the prayer of it sweep through him and he was always glad, then, that he had stayed alive. There was always something to make him glad – the sharpness of grass, or a rock exquisitely veined with red, or pollen touching the child's skin and leaving its stain.

Story time. He looked at the green sward, the medieval crags, the black brooding carriage, and he held his little girl by the hand. His Lily. His Rose.

By mid-afternoon words had left him again. He was not sure what remained in the pan of his skull, but the last thing to go was the mechanism whereby a man counted things. He could feel himself tick with each passing tree trunk, fifty, fifty-one, fifty-two – as though counting was the last tenacity. And then the numbers, too, were gone, and his thoughts were made of nameless rocks and trees, the nameless eyes of the child at his side, and the wide, nameless sky.

Dusk.

The evening, like the morning, was full of business, as he tended to Lopez. After which, there might be food, or even music. As he turned to sleep, his mind would snag on some domestic thing the girl had arranged for him, a hot stone against the mountain cold, or the girl's own body bundled beside him: he would feel his own smallness under the stars, and there, on the side of the cold hill, he would long for something that was the exact temperature of Venancia Báez. His fingers twitched as he fell asleep, fumbling for the gaps in her imaginary clothes, and the feel of her skin was intimate as oblivion to him, and as large, and kind.

He thought about the last night he spent with her in San Fernando, at the mouth of the Tebicuari. He could see her eyes in the dark. She was very clever, his wife. She had not come to the camp in secret – nor did she come openly. She came like a woman covered in dust, limping on bark shoes, and so she walked in past the sentries and then walked out again, back to the captured city of Asuncion.

She slipped into his hut after sunset, and looked at him.

Later he saw her body. Or some of it.

It was not just Venancia's body that Stewart had slept with in the early days of their marriage, but it was her body that was beside him now, as they lay and faced each other and talked – close, so as not to be overheard. The swell of her hip and the angle of her shoulder, her breasts falling out towards him in a line; it certainly was her body, or a swollen version of the same. But it seemed to him too lush, and hypocritical, now. Venancia's flesh, once so intoxicating, just irritated him: it made all the bites on his skin sit up. The whole pudding of it – his own starved, mortal shanks shivering beside her with something that might have been desire but felt more like tears.

'How do you live?' he had whispered, and she just smiled. Venancia grew things in the forest, or under the floorboards; she grew things in the dark. And even as he talked to her about a bank in Scotland, a broker in Buenos Aires, he was deciding not to touch her. She had given herself to some military fool, he decided, some Brazilian, saying, Ί have children to feed.' And how could he blame her? They were his children, after all.

Venancia's body. It filled the hut where they lay with accusation. It was not her fault. Stewart looked into her eyes (their brown plea) and knew that she might give her favours where she liked, but her life belonged to him. And all her cleverness, only to him. She had taken this journey, not to talk about money, but for love of him. Even so, the words that came to him were something like Ί do not', and then Τ do not', over and over again. A scrap of a phrase that begged many endings, one of them being -there was no doubt about it – Ί do not want you any more, Venancia Báez.'

High in the Amambai mountains, Stewart fingered the cold hair of the girl who slept beside him. It was brown. There was a white man back there somewhere, in her line. Some Jesuit.

'Poor William,' he wanted to say. 'Poor William Stewart.' Such scruples as he used to have. Now all he wanted was to hear the rasp and sigh of the girl's breath. All he wanted was to fling his life, one more time, into the body of Venancia (as was) Báez.

Later, he woke the girl to look at a low star which had gathered about it a light of great delicacy in the bone-coloured dawn. He was not sure she understood, but she sat easily on his legs and, after he had pointed and she had looked up, they stayed like that for a while, waiting for the day to begin.

She was younger, now. The farther they went in the northern hills the smaller and more helpless she seemed to him. So perhaps it was true. They were going to a more innocent place, after all.

In the morning, Eliza would climb on to the back of a cart and play the captive piano, still tied where it stood. She played ' La Palomita' while Lopez, as often as not, shot someone. He did it personally – there were so few men left to do it for him; but also, it must be admitted, he needed to do it himself these days, like a morning expectoration or a fart.

When the time came to shoot his brother, however, the massively incompetent Benigno Lopez, he spared the man no honour. He called upon the services of Bernardino Caballero, the highest-ranking officer he had left. Also he had everyone stand as though on parade. He signalled Stewart forward to check the condemned man's health and the comfort of his bonds. He pulled their weeping mother towards the stake, and shook her shoulder and cast her down, as if to say, 'See! See, what you have done to this woman your mother.' And Eliza, for the occasion, played ' La Palomita' standing up. She wore red.

Benigno was stripped down to his underdrawers, and the mound of his belly was immensely comical and afraid. It quivered and heaved, and was so inviting that Lopez could not help but cut him loose one last time, to send him careening around in a circle, snorting like a pig. Everyone roared. They kicked or spat, while Benigno squealed. He seemed to enjoy it, in a bitter sort of way. He squealed fantastically well, and then he squealed even better. Then Lopez gave a brief nod to Caballero, who had the man-pig pulled back to the stake and shot.