Beildeck, my servant, answered it. I heard him challenge the visitor, though the replies were so soft I could not make them out. The door creaked as it opened.

I leaned over and stared down. A figure emerged from the deep shadow under the arch into the lesser gloom of the courtyard. He moved slowly, hunched over a stick which rapped on the cobblestones as he walked. He stopped in the centre of the yard. Then, as if he had known I was there all along, he looked straight up at me.

My legs sagged; I groped for the rail.

‘Kaspar?’

A bitter, brittle laugh like the chattering of crows.

‘Hier bin ich.’ Here I am.

LXV

Rhineland-Palatinate, Germany

Nick didn’t know when he woke. The dark day and coarse curtains held the room in twilight. He’d been living in that sickly gloom for the last week, the light of railway carriages, street lamps, car headlights and bare bulbs. A fly drowning in amber.

But amber was cold; Nick was warm, radiantly so, wrapped in blankets and sheets and Emily. Her camisole had ridden up in her sleep so that her naked back pressed against his stomach, their bodies locked together in a single curve.

The heat of her body against his filled him with the glow of desire. He parted her hair so he could kiss the back of her neck; he caressed her bare arm where it clamped over the blankets. She turned her head towards him, her lips seeking his. He saw that her eyes were closed and held back, but she put her hand behind his head and brought his mouth down.

Desire billowed into lust. He ran his hand down over her thigh, then clamped his palm over her hip and held her against him, pulsing against her. She gasped; she pulled his hand away and dragged it up her body, so that he could feel her breasts through the tight cotton of her camisole.

She rolled onto her back and pulled him on top of her. He came willingly.

The next time he woke he was alone in the bed. His headache had gone but he was ravenous. Emily had dressed and was sitting by the chest of drawers, which she’d turned into an makeshift desk. She had the stolen library book spread in front of her, together with a poster-sized chart which she was annotating with a pencil.

Nick sat up. A tangle of memories that might be dreams, and dreams he hoped were memories, rushed through him. He blushed.

Emily looked over and gave a shy smile. ‘Sleep well?’

‘Mmm.’ He scanned her face for traces of regret, until he realised she was doing the same to him.

‘I don’t want you to think…’ she began. ‘I know I shouldn’t-’

‘No.’ That sounded wrong. ‘I mean, yes, you should have. Not should…’

‘I don’t want to get between you and Gillian.’

Nick’s tumbling thoughts stopped abruptly. ‘Gillian?’

‘I know what she means to you.’

‘You don’t.’ Nick threw back the covers and stood, naked. Embarrassed, Emily looked away. ‘Do you think when we find her I’m going to sweep her into my arms and ride off into the sunset.’

She jerked her head back and looked him straight in the eye. ‘Then why are you doing this?’

Nick held her gaze and realised he no longer knew the answer.

‘I’m going to take a shower.’

There was no shower; only a bath. He splashed himself in the lukewarm water as best he could, then dressed. When he came out, Emily was sitting cross-legged on the newly made bed, books and papers spread around her.

‘What have you got?’

‘I’m trying to pin down the links between Gutenberg and the Master of the Playing Cards.’

The exchange seemed to cement an unspoken agreement. Emily relaxed; Nick sat himself on the corner of the bed.

‘We have to assume Gillian didn’t see the page we pieced together. She must have followed a different trail.’

‘Right.’ Nick examined the large sheet of paper spread on the bed. It was covered in an irregular grid creased by folds; most of the squares were empty, those that weren’t held cryptic snatches of writing: ‘f.212r Bottom centre, similar.’ Characters from the playing cards in miniature line drawings ran down the left-hand column.

‘What is that?’

‘It’s a chart of books and manuscripts with illustrations that look like the playing cards. It lists which images appear where. One of them’s the Gutenberg Bible from Princeton I told you about.’

Nick slid off the bed and crossed to a low table by the door which held a kettle and a box of teas. ‘I don’t get it. If the whole point of Gutenberg is that all the copies are the same, shouldn’t they all have the same illustrations?’

Emily shook her head. ‘Like a lot of revolutionaries, Gutenberg dressed up his invention in very conservative clothes. People distrust change. He wasn’t selling novelty; he was trying to persuade people he had a better way of producing something very familiar. In this case, manuscripts. The same way that the first motorcars looked like horse carts.’

Nick filled the kettle.

‘In the Middle Ages, you didn’t buy a book like you do now. They were all part-works. First you found the text you wanted and got a scribe to copy it. He’d write it out on quires of eight or ten pages, which you’d then take to a bookbinder to have bound together and put between covers. Finally, you got a rubricator to write in the rubric, the chapter headings, in red or blue, and an illuminator to add the pictures. Just black, thanks.’

Nick took two tea bags out of the box and tossed them into the mugs.

‘Some of the early pages of the Gutenberg Bible show that he actually experimented with two-colour printing, so he could include the chapter headings as well as the body text. But he abandoned that very quickly – probably because it was too difficult and time-consuming. Gutenberg didn’t want to change the way books were produced – just the way the text was reproduced.’

Nick remembered a phrase from the back of the bestiary: ‘a new form of writing’.

‘I should have realised what it meant much sooner. But the answer to your question is that although the texts of the Gutenberg Bibles are all pretty much identical, every surviving copy is unique. Each was bound and illuminated by different hands.’

‘And the Princeton copy was done by the Master of the Playing Cards?’

‘Some of the pictures in the Princeton edition are close copies of the figures on the playing cards,’ she corrected him. ‘It could be that an illuminator saw the playing cards and copied them or that both of them drew from yet another source.’

‘Except that now we’ve got a piece of paper that puts Gutenberg and the Master on the same page of another book.’ Nick poured steaming water into the mugs. ‘Let’s assume it’s more than coincidence. Gillian must have.’

‘Agreed. Which is why I wanted to look at the illustrations from the Princeton copy. Maybe there’s some sort of pattern, a clue Gillian found.’

‘Any luck?’

‘Not yet. This chart only gives the page numbers. I need to see the text that goes with them.’

Nick stared at her. ‘I hope you’re not planning on stealing another library book.’