Jack snapped out of his reverie, took a deep breath, and looked hard at the mosaic and the painting. ‘Come on,’ he murmured.
‘What is it?’ Costas said.
‘It’s got to be here somewhere,’ Jack said. ‘If Everett left any kind of clue, it’s got to be embedded in these images.’
Jeremy walked up to the wall, and peered at the painted wreath that surrounded the chi-rho symbol. ‘Is this an exact copy?’ he asked.
‘He did make some changes,’ Morgan said. ‘Those pinnate leaves are walnut and the flowers are orchids, which he loved. He added the Greek letters too. I checked them all after I first came here, tried to match them with every known Christian acrostic, but came up with nothing. I’ve had to conclude they were purely decorative.’
‘That doesn’t sound like Everett,’ Jeremy said.
‘No, it doesn’t, but I’ve tried everything.’
Jeremy stood back, and looked all round the room. ‘What’s the chronology of this place?’ he said. ‘I mean, do we know when he did these decorations?’
‘I was able to speak to the Mother Superior, through an intermediary,’ Morgan said. ‘She’d been a young nun here when Everett was dying, and had nursed him in his shack during his final months. Apparently he’d finished building this part of the convent before the First World War, within two years of arriving in America. He seems to have worked with extraordinary fervour, as if he needed to justify the decision he’d made to leave his family and sacrifice his career.’
‘And the decoration?’
‘He finished the mosaics then too, including the word square at the entrance. But the wall painting he did when he returned from the war. When the Mother Superior was young, some of the older nuns remembered it. Everett had returned a changed man, withdrawn and troubled. Physically he was weakened, his lungs permanently damaged. He virtually locked himself in this room, for months on end. They had no notion of what he’d gone through. How could they? Southern California was a long way away from the hell of a gas attack. But you can see it in that painting. His version of the chi-rho is stark, jagged, pitch black, as if it’s been blasted by fire. It’s like those black-and-white photographs of towns on the western front, Ypres, Passchendaele, Loos, where he was wounded, utter desolation with only a few shattered fragments standing, like a bleak image of the hill of Golgotha, the empty crosses of the crucifixion blackened and warped by fire.’
Jeremy walked up to the wall painting, and traced his finger over the wreath. ‘I count twenty-five letters altogether, all Greek,’ he murmured. ‘No obvious order, no rationale. They don’t seem to read anything, forward or backward.’
‘I told you I’d tried that route,’ Morgan said. ‘Didn’t get anywhere. The only legible inscription is those words Domine Iumius at the bottom, below the Armenian cross. That doesn’t get us anywhere either.’
‘He was a brilliant mathematician,’ Jeremy murmured. ‘He loved puzzles, word games. You can see it in that word square at the door. Then he goes to war, comes back and does this painting, adding these letters to his copy of the Roman original. Why? What had happened to him?’ Jeremy stared at the wall, pressing on it with one hand and tapping his fingers, then suddenly turned and looked at Morgan. ‘Remind me, 1917. You said he came back here. You mean to the convent, where we are now?’
Morgan nodded. ‘After America had entered the war, after he’d been involved in decrypting the Zimmerman telegram. He and William Montgomery came here to California, to this place.’
‘Cryptographers,’ Costas said, his eyes narrowing. ‘Codebreakers.’
‘That’s it. I’ve got it.’ Jeremy bounded over to the bag he had left by the door, and pulled out a battered notebook. ‘Remember this, Jack? It’s what I was reading on the plane. I had a hunch it might come in useful.’ He flipped it open, thumbed through it and stopped at a page. ‘When I was at school, I transcribed the entire Zimmerman code,’ he said excitedly. ‘That’s what happened to Everett during the war. He’d been shell-shocked, wounded, but he’d also become a codebreaker. That’s the key. He returns here during the war, and wants to leave a clue, just as Claudius did two thousand years before. He’s immersed in codes, and he’s got the Zimmerman code running though his head. He lets Montgomery in on his secret. It’s the only reason I can imagine he brought Montgomery to this place, in the middle of the war when they must have had precious little time. Maybe they devised a code in this very room. Maybe the ancient document, the gospel, was somewhere here, concealed by Everett in this room while he was building it before the war, and maybe they planned a permanent hiding place for it when they were here together.’ He paused, and peered at Morgan. ‘You’re right. These letters don’t fit any ancient acrostic. But I don’t think they’re purely decorative. I think they’re a First World War code.’
‘Keep talking,’ Jack said.
‘The Zimmerman code was numerical, right?’ Jeremy flipped to another page. ‘The telegram looked like any other except instead of letters there were numbers, arranged in clusters like words. The problem was assigning values to the numbers, equating them to a letter or a syllable or a word. The breakthrough was the secret codebook acquired from a German agent in the Middle East.’
‘I think I’m with you,’ Costas murmured. ‘What about giving the Greek letters on the painting a numerical equivalent?’
‘That’s exactly what I thought.’ Jeremy rummaged for the pencil in his pocket, opened a fresh page and began copying down the Greek letters in sequence as they appeared on the painting, clockwise from the top where the two arms of the painted wreath nearly joined. He then jotted down the Greek alphabet from alpha to omega with the numbers one to twenty-four alongside, and transferred those numerical values to the sequence of letters from the painting, beginning with the first letter from the painting, delta, and the number 4. ‘Okay. I’ve got it.’ They crowded round, and he held the notebook up in a shaft of light. They could see the Greek letters with their numerical value below:? P Z T??? H?? H M?? I?? A? N? O? B T 4 17 6
19 14 21 23 6 24 8 6 12 4 8 9 16 24 1 14 13 11 15 16 2 19
‘Okay. It’s pure guesswork, but if I’m right there will be clusters in those numbers identical to clusters in the German codebook, and then we’re in business.’ Jeremy bounded back to his bag, pulled out a palm-sized computer and activated it, squatting down on one knee. ‘When I first became interested in the Zimmerman code, I decided to see how modern computer technology could have aided the decryption,’ he said.
‘I’m liking you more and more, you know, Jeremy,’ Costas murmured.
‘I’m sure Everett would have loved the technology,’ Jeremy continued. ‘But he would have seen that with some decoding, no amount of computer wizardry can replace the human brain. Decrypting the Zimmerman code depended on understanding the Germans who created it, their perception of the world, their vocabulary. You had to know the words they would have used and been familiar with.’
He tapped a command and a page of numerical sequences came up, with words and syllables alongside. ‘As it turned out, the key to the German code was quite simple,’ he said. ‘Each cluster of numbers is a word or a phrase or a letter. You use the codebook like an index. The problem was, the Germans who created the code hadn’t anticipated some of the words that were going to be needed for this particular message, so a few words had to be made up from smaller parts. Here, you can see the word Arizona, made up from four different clusters of numbers, for the syllables AR, IZ, ON and the letter A. That’s the part of the Zimmerman telegram where the Germans were going to help the Mexicans reconquer the southern states. The intelligence people back in Germany had never imagined they’d need the word Arizona, evidently. This was probably where Everett came in. He may have been more familiar than any of the other British codebreakers in Room 40 with America, having lived there for several years before the war. He may have been the one who suggested that they should be looking out for geographical names, unique place names that might not be in the codebook.’ Jeremy paused, tapped the keyboard again and sat back. ‘Okay. I’m going to run these numbers. This might take a minute or two.’