Nevado picked up the bestiary. ‘This was the book you brought?’

Nick didn’t answer. He had a terrible feeling nothing he could say now would save them. The overpowering smells of gasoline and tobacco made him sick.

Nevado opened the cover. One glance was enough.

‘This is the wrong book. A simple bestiary.’ He swept the book aside and turned to Gillian, his waxy face flushed with rage. ‘You told me they would bring the Liber Bonasi.’

‘There’s a colophon,’ Gillian stammered. ‘It mentions the other bestiary. That’s how we knew. It led us here.’

‘This is worthless.’ Nevado leaned on the shelf, seemingly oblivious to the cigarette dangling inches from the packed books. Nick barely noticed. Something the cardinal had said echoed in his mind like a gunshot. You told me. He turned to Gillian.

‘You told him we were coming?’

‘Of course not.’ She reached to her shoulder and began twisting a lock of hair around her finger. ‘I told him the book I found in Paris was the one he wanted. I had to. He must’ve thought you’d bring it if he lured you here.’

She looked him straight in the eye, begging him to believe her. Nick wanted to; he almost had when Emily said quietly, ‘How about the note? Your set of instructions on how to break in.’

‘I don’t know. He found them when he captured me. Planted them where you’d find them.’ She saw Nick’s expression. ‘What?’

‘Do you know where he hid them?’

Gillian stared at him. He recognised the look: he’d seen it before. In trouble with someone, searching for the answer they wanted to hear. She began to speak, then checked herself.

‘He hid them in the toilet roll,’ said Nick. ‘Did you tell him about that?’

She crumbled. He’d seen that before too. ‘I had to, Nick. He’d have killed me if I didn’t go along with it.’

‘And what did you think he’d do to us when he caught us and found it wasn’t the right book? Tell us it was all a misunderstanding and let us go?’ His head pounded; his eyes hurt just to look at her. He felt as if he’d turned to stone.

‘Enough.’ Nevado turned, his face hazed in the smoke of the half-smoked cigarette. He shouted something in Italian to the guard at the door. ‘I have decided-’

Without warning, Gillian flew at him. Before the guard could react she had snatched the cigarette from Nevado’s mouth, pivoted away and hurled it into the bookshelf. The oil-soaked papers took the flame eagerly, as if they had waited five hundred years for the consummation.

‘No!’

Too late, Nevado seemed to change his mind. He ran to the shelf and pulled the burning papers to the floor, frantically stamping on them. A gust of wind from the door picked up the loose leaves and blew them against the shelves, starting new fires higher up, out of reach. The hem of Nevado’s coat caught fire.

Then the whole wall exploded in flame.

LXXXIV

Through the gathering smoke, Nick saw Nevado run for the door. He tried to follow, but a rattle of bullets answered him almost immediately. He dived for cover, pulling Emily down with him and covering her with his body. When he looked up, he was just in time to see the door slam shut.

Where was Gillian? He looked around through the black smoke pouring off the books and couldn’t see her. Had Nevado taken her with him? Was that part of the deal?

Then he saw her. She was lying on the floor near the shelves, propped up on her arms trying to crawl away. Hot ash and embers rained down on her, curling like petals on her back, but she didn’t move any faster. She couldn’t: when she tugged her leg forward a dark river of blood smeared behind her. Nevado’s parting gift.

Nick ran over, hooked his arms under hers and dragged her to the middle of the room. Emily tore a sleeve off her sweater and tied it around Gillian’s thigh to staunch the bleeding. Her face was white with shock.

‘I’m sorry,’ she mumbled. ‘I’m so sorry, Nick.’

There wasn’t time. The flames were already beginning to spread from the back around to the sides of the hall. Smoke was filling the chamber. Nick pulled his gloves out of his pocket and handed one to Emily.

‘Hold this in front of your face.’

Breathing through the soggy wool Nick raced to the door. The surface was smooth and featureless, with neither lock nor handle visible.

Did you think we are so trapped in the Middle Ages that we do not even know how to lock a door?

He gave it a kick, but it didn’t so much as creak. He only hurt his foot. He pressed it with his hands and felt the grainless strength of metal. They would burn long before it did.

He ran back to Emily and Gillian. ‘Bad news.’

Without taking the glove from her face, Emily pointed up. Thick clouds of smoke swirled among the rafters. She snatched the glove away just long enough to say, ‘The smoke. Going out.’ She took another breath. ‘Must be an opening. In the roof.’

Was there? Nick had his doubts. But there wasn’t any other way out. He stared up at the shelves, like a giant stair scaling the high wall. Ladders and galleries connected them, though some were already dangerously close to the encroaching flames. Even if they made it to the top, they’d probably just find themselves trapped.

Got to keep trying, he told himself. He put his arm around Gillian’s shoulders, lifted her up and headed for the nearest ladder.

The cold air in the courtyard was a mercy. Nevado dropped to his knees in the snow to extinguish the last embers smouldering in the hem of his coat, and to cool the burns that scalded his legs. Ugo watched him uncertainly.

‘Should we put out the fire?’ he asked.

Nevado looked back. From the outside, the inferno inside the keep was all but invisible. The windows in the tower had long since been blocked up. Only the smell of smoke, almost comforting on this snowy night, gave any clue. The plume pouring from the roof was lost in the darkness.

‘Are you OK, Monsignóre?’

Nevado realised he was trembling. He had not meant it to end like this – rushed and sloppy, out of his control, Pope Pius’s commission still incomplete. And the sight of all those books burning – evil though they were – had shaken him more than he had expected.

But the Lord moved in mysterious ways. Perhaps it was a gentle correction, he thought, a warning to his pride that only God was perfect. His plan would still work.

He turned to Ugo. ‘Give me your weapon.’

Ugo looked surprised, but handed him the pistol without complaint. Nevado felt the weight of it. It was so much smaller than the guns he’d used in his youth, protecting himself against the republican gangs who lurked in the forests around his father’s church in Andalusia. But the mechanism was the same. He checked the clip and the safety.

‘Bless you.’

He fired two shots into Ugo’s chest. The Italian collapsed without a sound, his blood seeping into the snow like ink.

They overpowered the guards and could not be stopped. It was regrettable but necessary. No one could blame him for inadequate precautions.

Nevado gave him one more bullet, just to be sure, then threw the gun into the snow by the keep. Whoever came to investigate could draw their own conclusions. Then he hurried to the stables where his car was parked.

The back wall of the tower was awash with flame, like a stained-glass window leaded black where the shelves had not yet collapsed. It sucked in air and turned the whole chamber into a vast oven. At the far end of the room, Nick had stripped to his T-shirt and was still soaked through with sweat. His shirt was tied around Gillian’s leg, strapping on a makeshift splint made from two lengths of bookshelf. She clung to the shelves as she hobbled along the gallery.

The walkway was metal, a cast-iron lattice so that when you looked down, you could see how far you had to drop. It wouldn’t burn, but it might fry them. Nick could already feel it getting hot through the soles of his shoes. So far, the stone pillars had stopped the flames from spreading to their part of the library, but it couldn’t be long. A blizzard of burning paper scraps swirled in the hall on currents of smoke and scalding air.