Ferron leaned over her. 'All you have to do is look at me,' he murmured. 'Just look at me and I'll tell them to stop.'

But, though she jerked and thrashed her head against its metal bond, she kept her eyes closed. Ferron nodded for the brothers to continue.

As the brothers poured more water into her, bucket after bucket, and more of the cloth was drawn into her throat and belly, and her stomach began to bloat, a grotesque swelling under her gaunt ribs.

Geoffrey, in torment himself, understood the logic. Ferron, as a man of God, wasn't supposed to draw blood. And nor was he supposed to allow his victims to die. This punishment with water, which would leave no mark, was a method devised with stunning ingenuity to fit this contradictory logic perfectly. It was even cheap, for the cloth and metal frame could be used again.

A full hour after it had begun, still Agnes would not speak. So Ferron nodded to the brothers, who lifted up the ladder, with the girl's broken body still fixed to it, and turned it so her feet were higher than her head. As her bloated belly pressed on her heart and lungs, through her crammed throat Agnes let out an animal roar of pain and terror.

Geoffrey could stand it no more. He lunged at Ferron. 'You monster, Ferron! How can you imagine that this serves the purposes of Christ?…' But a brother grabbed him, pinning his arms.

On the morning of the execution of Agnes Wooler, Geoffrey Cotesford came early to the place of burning. It was another grim February day.

Eight years after the first auto-da-fe, the burning place outside the walls of Seville had come to be known as the quemadero. A platform had been set down here, with blunt stone pillars, strong and reusable. On the four sides of the platform statues of prophets stood, glaring sternly at those brought here. This morning, wood was piled up around each of the pillars.

From this place hundreds of souls had already been despatched, wisping to heaven or hell like the greasy smoke from their owners' crisping bodies.

As the morning brightened, others gathered for the show, men, women, even some children. Geoffrey had expected that. But the mood among these onlookers was not as he had anticipated. They seemed dull, almost numbed. Perhaps the Inquisition had dug too deep into the vitals of the nation. You came to watch, but not with relish, for you could not be sure you were safe yourself.

At last the procession reached the quemadero. The crowd murmured and shuffled, and some crossed themselves. Led by Ferron and other inquisitors and flanked by soldiers of the Holy Brotherhood, there were perhaps twenty of the condemned. All carried lit candles. The men walked barefoot, and their feet were white from the cold. But the women were stripped naked, and though their bodies were shrivelled from their captivity they had to suffer taunts from the crowd.

It was this type of detail, this repulsive lasciviousness at a place of death, that convinced Geoffrey that whatever motivated the Inquisition it was nothing to do with God. If Christ were here, He would surely have stepped forward to protect these suffering ones, even if it meant He had to die in their place. But Christ was not here. Only Geoffrey Cotesford, weak, cold, ashamed.

There among the huddle of women was Agnes. Geoffrey was surprised she could walk at all. She carried her candle in one hand, for her other arm hung limp. The shoulder looked dislocated; the pain of it, weeks after her first punishment, must have been agonising.

He couldn't help but call, 'Agnes!'

She looked around dimly. Her eyes seemed unfocused.

He didn't know what to say. 'I'm sorry,' he said. 'I'll pray for you. I can't help you-'

'I can, though.'

The voice in his ear was startling. It was Abdul Ibn Ibrahim, and he was grinning. He held a bundle of documents.

'Abdul? What are you doing here?'

'Being my deceitful, conniving, conspiratorial self.'

'I don't understand.'

'The Inquisition,' he said, 'is the logic of our times – of your times, of this age of Christendom. The Reconquest and all your crusading has militarised Christianity, which was once a faith of love. Frightened and ignorant, terrified by the march of infidels, stirred up by holy fools and greedy monarchs, you fall willingly into the thrall of these perverted prelates. Well, there's nothing I can do about the flaws in Christian souls. But perhaps I can save one helpless woman. Come.' And he strode forward, boldly approaching Ferron.

Geoffrey, confused, could only follow.

Abdul stood right in front of Ferron, forcing the whole procession to stop. The situation couldn't have been more public, with the inquisitors, the brothers, the crowd, even the condemned looking on.

Ferron glared at Abdul and asked him why he was here.

'It's a matter of grave concern,' Abdul said. He tapped his sheaf of documents. 'I must discuss it with you.'

'What, here? Now?'

'There is no time to delay. Please, brother. It is a matter of death, or life.'

'Whose life? Whose death?'

'Yours,' said Abdul.

Ferron stared. Then he allowed Abdul to draw him aside, but he waved the procession forward. As the brothers made the condemned kneel before the posts, he snapped, 'Make it quick, mudejar.'

Abdul indicated the sheaf of papers. 'A witness has come forward. To testify against you, brother. He has the testimonies of others to back him up.'

Ferron stiffened. 'And what is his allegation?'

For answer, Abdul held out his hand. It contained a round sliver of bread, a communion wafer. 'This was found in your office.'

And Geoffrey immediately understood.

At the heart of the crimes routinely alleged of conversos, supposedly lapsing from Christianity to Judaism, was the theft of consecrated wafers. It was easy; when fed it by a priest you could just slip a wafer under your tongue and keep it there, unconsumed. But, once consecrated in the Holy Mass, its substance had been transformed into the flesh of Christ, and so the wafer held potent magic. For example, some years back there had been a rumour of a conspiracy to spike the water supply of Seville with communion wafers and the mashed-up heart of a Christian boy, a blasphemous toxin that would drive Christians insane.

There was fear in Ferron's eyes; it was well known he was of converso blood himself, and this was a silent accusation of a very grave crime. 'Who gave you this?'

'Well, you aren't entitled to know that,' Abdul said. 'Strictly speaking, by the rules of your Inquisition, I shouldn't be showing you this evidence at all, for you don't have the right to see it. And of course you are presumed guilty once an allegation is made. Have I got that right?'

'It's a lie. An evil, devil-spawned, malicious lie.'

'I'm glad to hear it,' said Abdul heartily. 'Then the processes of the Inquisition will have no difficulty establishing exactly that fact. But perhaps it would be better to save everybody the trouble of putting you to the question.'

'What is it you want, mudejar?'

'Agnes Wooler.'

Ferron stared at him, and then looked at Geoffrey. 'I nearly broke this girl seeking answers about her conspiracy. But those answers were staring me in the face, all the time. If I ever see you again-'

Abdul grinned, and he held up his fist, enclosing the host. 'Threats are so ugly.'

Ferron turned away. He walked onto the quemadero, grabbed Agnes by her good arm, and marched her away from her stake. Another inquisitor flapped after him, muttering about irregularities, but Ferron waved him away.

He brought Agnes to Abdul and Geoffrey. She looked grotesque, her feet and hands blue with the cold, her nipples hard as pink pebbles. Her bruised face was empty.

Abdul dropped the communion wafer into Ferron's hand. In return Ferron released the girl. She stumbled, and Geoffrey took her thin, shivering form in his arms.