2001, New York

‘But those letters, they don’t spell anything!’ said Maddy. ‘They’re just a bunch of weird Celtic squiggles.’

Adam was looking around her messy desk for something. ‘It’s not the letters we want – just where they are on the page. Have you got any cardboard?’

Normally there were half a dozen pizza boxes lying around, but she’d binned a whole bunch of them the other day. ‘Uh? What do you want cardboard for?’

Sal looked around at the filing cabinet to the right of the computer table. Liam had left a breakfast bowl up there and, being the scruffy shadd-yah he was, the box of Rice Krispies. She reached for it.

‘This any good?’

Adam grabbed it. ‘Yeah. Scissors?’

Both girls shook their heads.

‘This isn’t a freakin’ craft store,’ said Maddy.

‘I need to cut out windows,’ said Adam. ‘Have you got anything? A penknife?’

Cabot reached into the folds of his monk’s habit and pulled out a small knife. ‘Would this do?’

‘Perfect.’

Adam grabbed the knife from him. He pulled the bag of Krispies out and then began to hack at the cereal box. Maddy frowned. ‘You gonna make something you saw on Sesame Street?’

Adam ignored the jibe and pointed at the computer screen. ‘Make a note of those stand-out letters.’ He took his cardboard box and Cabot’s knife across to the kitchen table where the Treyarch was still stretched out under the glare of the overhead light.

He finished cutting one side of the cereal box out and laid it gawdy, print-side down on the parchment, carefully lining up the ragged corners of the cardboard with the corners of the margin illuminations.

‘Too big,’ he muttered. He began trimming one side. Cursing as Cabot’s serrated blade chewed at the flimsy cardboard, leaving a rough, uneven, shredded edge.

Sal, Cabot and Becks joined him.

‘This’ll be no good for cutting out the windows,’ he said. ‘I need a modelling knife or something. The cardboard’s just shredding up.’

Sal looked down at the parchment. ‘Why not just cut the letters out of this Treyarch thing?’

Adam looked at the ragged wobbling scrap of cardboard in his hand, then down at the unravelled scroll. ‘Yeah, why not.’

Cabot’s eyes grew round. ‘But – but … ’tis a valuable account from the First Crusade!’

‘No,’ said Adam, ‘it’s a cardan grille in disguise. That’s all it is. That’s why it was written. It’s the real key to that,’ he said, gesturing at the wooden box perched on the end of the table.

Maddy rushed over with a sheet of paper in her hand. ‘I printed it out.’ She laid it down on the table, the highlighted characters still just about discernible from the rest of the text. ‘OK,’ she said, ‘this first line … it’s this character that’s highlighted,’ she said, pointing to the upside-down Gaelic symbol Cabot had noted minutes earlier.

Adam took the knife, and carefully dug its sharp tip into the parchment and the wooden table beneath.

‘What if we’re wrong?’ said Maddy. ‘What if it’s something else? You’re about to cut holes in this thing, and, like, there’s only this one copy!’

Adam hesitated a moment. ‘Ahh … true.’ He blew air through his teeth.

She looked down at the printout. ‘But looking at that …’

He nodded. ‘Exactly. Those letters are different ink. There’s only one reason you’d write certain letters out of order like that.’

‘Yeah …’ she shrugged. ‘Ahh heck – go for it, then.’

As Adam began cautiously cutting the first character out of the stiff parchment, Cabot absentmindedly crossed himself with the tips of his fingers and muttered an apology in Latin to God above.