horizon, had been swallowed whole by Black Sea clouds, hanging like a dank curtain, obscuring the mountaintops. The air was as heavy as grease, stirred fitfully by a reluctant breeze. The sea, as they ascended, looked less and less real, appeared creased, solid, like a sheet of aluminum foil.
Once, they would have risen toward the Zigana Pass on the backs of sure-footed horses or stout donkeys laden with goods bound for the interior of Anatolia or, if they were enterprising enough, beyond, following the long and treacherous camel route all the way to Tabriz, in northern Persia. In their case, Khalif's rattletrap car would have to do, spewing sulphur-dioxide particulates every time he changed gears. The car was full: in the backseat, the Glimmer Twins, heavily armed, consulted their cell phones as if they were the Delphic Oracle. The phones, wirelessly connected by satellite to the Global Positioning System, gave them a god's-eye view of the trip. They were in contact with their brethren, Kartli's people, deployed in strategic positions, monitoring the traffic along the car's route through high-powered field glasses.
Bravo's cell phone gave a stuttering burr, but when he answered it, the signal was gone, with no record of who had called. He thought, then, of Emma, dutifully cross-referencing the London intel Dexter had assigned to her. He found he very much wanted to talk with her, as if hearing her voice would restore a semblance of the equilibrium he had lost with each betrayal, each death.
He held the slip of paper his father had interred beneath the tile of oltu tasi at the Zigana Mosque, along with his father's notebook. The cipher was a long one, a veritable bitch, and Bravo was having great difficulty decrypting it. Part of the problem was that the cipher seemed as if it was incomplete, but he knew that couldn't be.
Beside him, Khalif kept up a steady stream of stories from the Order's past, mostly about Fra Leoni. 'Fra Leoni was both a genius and a saint, and here is why. Have you heard of Leon Alberti?'
Bravo glanced at him briefly. 'Of course. He was the father of the Vigene`re cipher, the greatest cryptologic breakthrough in more than a thousand years. He was also a philosopher, painter, composer, poet and architect. He designed Rome's first Trevi Fountain, and it was his book, the first ever published on architecture, that sparked the transition from the Gothic to the Renaissance style.'
'And who do you suppose ensured that his book was published?' Khalif said.
'I have no idea.' Part of his mind was still working on the perplexing cipher.
'His good friend and confidant, the man from whom he learned the philosophy of cryptography on which the Vigene`re cipher is based. Fra Leoni.'
His interest sparked. 'So Fra Leoni was the cipher's godfather.'
'Exactly so.' Khalif nodded. 'Shortly after taking over as Magister Regens, Fra Leoni discovered that a number of the Order's secret ciphers had been intercepted and decoded by the Knights. He knew it was essential that he invent an unbreakable cipher system, and he had the basis of an idea. Instead of a substitution cipher, he wanted to work on the notion of using two cipher alphabets simultaneously-the first letter of the message would be encoded using the first alphabet, the second letter encoded with the second alphabet, the third letter encoded with the first, and so on. He reasoned, quite rightly, that employing two alphabets instead of the traditional one would thoroughly confuse anyone attempting to break the cipher. To this end he recruited Alberti to aid him in his quest.
'This was around 1425, but Alberti died before he had completed his task of a fully formed method of encryption. Over the years, Fra Leoni turned to others in the Order: a German abbot, an Italian scientist and, finally, a French diplomat, Blaise de Vigene`re, who Fra Leoni contrived to have assigned to Rome. This was in 1529. Fra Leoni showed him Alberti's original treatise, along with the notations of the other members of the Order. It took Vigene`re and Fra Leoni another ten years before the cipher was engineered to perfection.'
'And for the next two hundred years or more it was unbreakable, so it must have served the Order well,' Bravo said. 'The British cryptographer Charles Babbage broke the Vigene`re cipher in 1854.'
'Ah, but his discovery was never published in his lifetime.' Khalif rumbled off the road briefly to bypass a herd of goats, who looked at them with slitted demon's eyes. 'It wasn't until the 1970s that-'
'Wait a minute,' Bravo said, 'you're not telling me that the Order had something to do with the suppression of Babbage's breakthrough.'
'Charles Babbage was a member of the Order.'
'What? Explain this to me.'
'Under no circumstances.' In a death-defying maneuver, Khalif pulled out into the oncoming traffic lane to surge past a truck whose diesel engine seemed on the verge of issuing a death rattle. 'In this I must be your father's advocate. You have enough information to work out the solution for yourself.'
The rearview mirror revealed that the Glimmer Twins were knee-deep in their own excited conversations. It was going well, then. Bravo tried not to be inordinately pleased, but he couldn't help himself. At last things were turning his way. Except for this damnable cipher his father had left him, whose key still eluded him.
Redirecting his thoughts to the problem Khalif had proposed, he said, 'If I were Fra Leoni and had spent so much time and mental energy on creating this polyalphabetic cipher, if I was going to depend on it for the Order's secret communication, I'd want to make damn sure it couldn't be broken.'
'How would you do that?'
'I'd use the same method I'd used to create it-put a team together to work on breaking it.'
The twinkle in Adem Khalif's eye heartened Bravo; he was on the right track.
'And once they had broken it?'
'I'd make damn sure no one knew about it until I could come up with another, even more secure cipher. Which the Order must have accomplished in 1970.'
'Quite right.'
Bravo shook his head in awe. 'And shortly thereafter, Babbage's discovery was made public.'
'That was your father's doing.' Khalif gave him a brief glance. 'You know it was your father who invented the new cipher-the Angel String. Fra Leoni having died some decades before, it was your father who took up his torch. It seemed to me that he had an almost mystical bond with Fra Leoni.' He shrugged. 'Perhaps-I don't know this for a fact, you understand-your father managed to meet Fra Leoni. Don't give me that look, it's altogether possible, you know. When your father put his mind to something, he almost always succeeded.'
The Angel String was his father's creation-he should have known that because his father had talked to him about how the Vigene`re code was broken: a method was devised to determine the length of the keyword. The cipher was then broken down into sections corresponding to that number of letters. These manageable chunks were then analyzed for letter frequency. The whole idea of the next-level cipher, his father had told him, was to do away with the keyword. But then the encoder would be mired in a jungle of multiple alphabets without a place to start his encryption.
Then something clicked in his mind. Drawing out the lighter his father had left him, he opened it, slid out the photo of Junior. Odd that his father had chosen a black and white shot that had been hand-colored: red, blue, green… In fact, now that he looked at it closely, Junior's face was yellow, not flesh-colored.
Turning to a blank page of his father's notebook, he jotted down the colors of the visible spectrum. It started with red and ended with purple. Assigning a number to each color brought him to 1543. So he was to use the first, fifth, fourth and third alphabets in that order. Referring back to the Vigene`re grid he had used before, he began his decrypting.
Behind him, the conversation of the Glimmer Twins became more intense. He ignored it for as long as he could, until their excited chatter filled the interior of the car. By that time, he was halfway through turning the cipher into plaintext and was already deeply troubled by what he'd read.
Tearing himself away from his work, he turned halfway around in his seat.
'A sighting?' he said.
'Here's where we are,' one of them, whose name was Bebur said, pointing to a screen glowing like a fusion reactor.
'And here's Damon Cornadoro,' Djura, the other, said. Beneath the bandages, his nose was dark and swollen where Bravo had struck him in the Zigana Mosque. 'His truck is a half kilometer behind us.'
'Excellent. The plan is working.'
'Not exactly,' Bebur said. 'Mikhail gave orders to shoot him on sight. Somehow, he managed to completely elude the ambush. He's still behind us.'
'What did he say?'
