Ά riot,' they said afterwards. Ά complete riot.'

In the stalls the white-clad Indians press forward and lift their faces to the stage, all at the same terrible angle, while men hack at each other with wooden swords and 'Gadzooks!' 'Have at thee!' they cry. At first, it comes from nowhere, a low groan, the rough keening of someone trapped by the action on stage (where they are losing – the Indians of 1750) and then it is all around, it is everywhere – the crowd is growling.

Few people here have seen the sea, the great mournful mass of it, so who could describe the waves of sound that helplessly break against the proscenium's retaining wall? Some of the rich have travelled but as they watch the stage they feel the rough utterance enter through their boots, to lodge in the base of their own throats. As for the foreign diplomats, the engineers and railwaymen, they do not even hear it – transfixed as they are by the thought that the people on stage manifestly cannot act, and so must be killing each other for real.

And when the stage is filled with bodies and pig's blood, the tide ebbs.

Thank God for plot, thinks Stewart, as the maiden walks out into that open, astonishing space to unmask her (very white) lover for the Guarani Prince he is. And so, the play proceeds, in all its lovely irrelevance. The prison scene, the duet through the bars, the firing squad, the huge roar of the rescuing lion, the cameo appearance of the King of Spain (old Lopez in his box deader than ever), forgiveness, penitence, tears and…

Actually, no applause. Silence.

Why do they not clap? The truth is that most of them do not know that they should and the rest check with old Lopez. But old Lopez sits unmoving while, in her central box, the heavenly Eliza Lynch looks merely smug, as though she had created this too.

The Dictator rises to leave. Perhaps he knows that the play has killed him. Or perhaps not – at the time it is neither rebuff nor disdain; it is simply a man turning, painfully, to go. It takes a foreigner, the young poet Hector Varela, who has come all the way from Buenos Aires for this night, to start a snide and rebellious act of applause that crackles briefly through the crowd and then stops.

Just before dawn, the crisis came. It hit him in the chest. And with it, he told Stewart (who was still in his evening clothes), a preternatural flush of horror.

When Stewart looked at the paper that Milton (or was it another Indian?) handed him the next day, his first thought was that Eliza wanted to know when the old man would die.

Tlease come.'

He read the note and stalled. He took a glass of Madeira. Then he shouted for his horse and fumbled his foot into the spinning stirrup (he was a fool, she was dying!). He tried to pace the ride to La Recoleta but it was the only straight road in the country, after all, and the horse galloped the length of it to haul him up, sweating, at her door.

He was shown up to the drawing room – which was, indeed, a glorious sight: it was some moments before his eyes got used to it, and yet another before he saw that Eliza was already there, sumptuously seated among her things. At first he mistook her for another objet; her face was made so tiny by the billow of watered grey silk about her on the ottoman. But it was Eliza, and she was very pale.

The doctor thought with a shock that she was lost, or drowning, that perhaps she would sink under the weight of it all. He stepped forward. She offered her hand, as though it were yesterday.

'Whatever I can do,' he said, and kissed it.

'Can you keep a secret?' she said. And then she smiled.

It all happened, he thought later, so quickly. As though they had both foreseen it, this room, his lurch forward, her hand under his lips. There was an understanding, but he could not tell what it was. And so he followed her down the corridor to a distant door with no sense of what might be behind it, except that it would be everything, and his head was almost spinning as they stood outside. She turned to him with a grave look. And then she opened it.

Stewart had no idea when she left. There was a shudder of grey beside him and, when he looked, she was gone. In front of him, sitting on a chair, was a woman in a good dress. Perhaps it was one of Eliza's. A silk dress, in pink, with the skirts arranged somehow to resemble a rose. The pink, he thought, was wrong. It brought out the redness in the woman's face, which was to say the redness of the flesh where her mouth should have been. Also where her nose should have been, but was not.

He thought he knew the eyes. Of course, they were the eyes of every woman who sees death come in the door. Or perhaps it is life they see. The desperate eyes of the dying, that long for something – and it might be you, Doctor Stewart.

'Francine,' he said.

The woman's tears were a torment to the open meat of her face and he told her to stop crying, please, if she could. He tilted her by the chin towards the light and got her to open the remains of her mouth so he could assess the state of her throat. It was a classic presentation, with ulcerations of the nasal and buccal cavity, disfiguration of the vocal chords. He put his fingers to his lips, in case she should try to speak.

'You had a lesion on your skin, some years ago,' he said, and she nodded. And so he proceeded to tell her what she already knew.

Eliza was not outside when he left the room. There was an Indian in the corridor – almost definitely Milton -who took his script and, rather brazenly, read it aloud. To counter which unlikely erudition, Stewart said,

'Lutzomyia, you know,' and Milton said,

'Sandfly. They like white meat.'

Stewart wished he would stop being a vulgar, clever man, and start being an Indian again, and this irritation kept him busy all the way back to the bottle of raw cane alcohol at home. He had Scotch, but this was not a Scotch occasion. Scotch would make him weep.

And the next day, from Eliza, a gift – a basket of cherries, red as an old wound, their delicate stalks and their thick, dark skins no more miraculous than the ice in which they came.

When Stewart next called to La Recoleta, he found Eliza playing diabolo in the courtyard with the only son of Juana Pesoa, the abandoned mistress of Francisco Lopez. The doctor looked at the dazed, ardent eyes of the boy (who was far too old for such games), and faltered.

'Go on, now. Run along!' said Eliza, and the young man, in a clumsy imitation of childhood, dashed into the house.

'Poor child,' she said, when he was gone. 'His mother is dying, you know.'

She said it so perfectly – perhaps she meant well. And to fill the doctor's silence she took his arm and said,

'You know, Doctor Stewart, I am the most fortunate woman in Paraguay. So it is a sort of motto with me – one must always include.,'

Stewart looked at her birds. There was, indeed, a vulture, chained to a stake in the corner, and it was very beautiful. He did not want to touch the woman at his side. He did not want her hand on his arm.

She enquired after his lodgings – did he have a garden? And his aunt, was she well? When all this failed she signed to a servant,

'You must meet Pancho,' she said.

Her son. Whose heart he had heard fluttering through this woman's thick skin. He must be four or five by now. The stories told of a little animal, who bit his nurse and would not learn to read, but when Stewart saw him appear in the doorway he thought him pure beyond the normal purity of children, he thought him pure like a flame. And so his mother played out her scene. She ran forward and embraced him; her lovely knee bent, her lovely silk in the dust. The child fought to be clear, and started to talk, and the angle their faces held was so perfect, the distance between them so radiant and careful, that Stewart forgave her – of what crime he did not yet know. This was the antidote. This was what he wanted. This. He wanted to possess, not the body of a woman, but the still air between her downturned face and the upturned face of her child. Air that is shaped by cheek and eyelash, by smiling lips and hopeful, reassuring eyes. He did not want to have a woman – not even this woman, Eliza Lynch – what he wanted was to give some woman, or to take from some woman, his son.