“At least that is one concern we’re rid of,” said Johann, slumping down beside Greta and wiping soot from his face. “That bastard will never lie in wait for us again. He is burning in hell, in the truest sense of the word. He didn’t have Sebastian, though. I suspect he’s already delivered the boy to Tonio.”
“Don’t you think you owe us an explanation?” asked Karl.
Johann raised an eyebrow. “What do you mean?”
“If I didn’t know better, I would believe you had conjured up some sort of hellfire. But I’m guessing it was the contents of your bag, which you lit with your torch just before throwing it.” Karl pointed at the flickering stump of a torch that the doctor had stuck into the ground next to him. “So? What was in the bag? I’ve never seen anything like it before.”
“It . . . it’s a weapon that no longer exists.”
“What are you talking about?” Still visibly in pain, Greta looked at her father. “It’s something to do with that accursed alchemy, isn’t it? What did you brew up?”
“It . . . it was more of a coincidence. Although I was hoping it might work. I had most of the ingredients, but no time to combine them according to the exact recipe. In all the commotion the various substances must have started to mix and—”
“What recipe are you speaking of?” asked Karl impatiently, sitting down beside the doctor, who was stinking of smoke and sulfur like a veritable demon.
“I’ll have to tell you at some point, so why not now?” Johann sighed deeply. “We talked about Constantinople earlier, the city of Emperor Constantine, formerly Byzantium. As far back as the time of the Greeks, a certain knowledge was gathered there which was kept secret from the rest of the world, and for good reason.” His jaws clenched. “It is just like Leonardo da Vinci once said. Some knowledge ought to never see the light of day. And yet it happened.”
“My son is held captive somewhere around here,” urged Greta. “And you are delivering a lecture. If you’ve got something to tell us, spit it out.”
“It is important for you to understand,” replied Johann, turning to Greta. “You especially. It’s something to do with your son. My grandson.” He swallowed hard and continued. “About three hundred years after the founding of Constantinople by Emperor Constantine, a new power entered the world’s stage, a power that swallowed up entire empires. They were fanatic peoples from the deserts of the east who turned up outside the walls of the city. No one had been able to stop them. Not the Sasanians or the Egyptians. It seemed as if all of Europe would soon be under their rule. During those dark times, a Greek inventor by the name of Kallinikos fled to Constantinople. He brought with him an ancient secret, a forbidden recipe, and he refined it. It would be the most terrible weapon the world had ever seen.”
“My God,” whispered Karl, who suddenly had an inkling what had killed Hagen. “Are you saying—?”
“The Byzantines called this weapon igró pir, liquid fire,” continued Johann. “The recipe was a state secret and included resin, sulfur, lime, saltpeter, and most importantly, an ingredient that in our climes is more commonly used in healing salves. I am talking about rock oil, or petroleum, as the Greeks call it. The effect is enormous. The Byzantines used pressure pumps, so-called siphons, to shoot igró pir at the ships of the Arabs. The sea turned into an inferno because the flames couldn’t be put out. On the contrary, they spread on the water. Thousands of soldiers died in this sea of fire, the ships of the Arabs burned, and the siege of Constantinople was abandoned.”
“That’s why it didn’t matter that the bag was wet,” Greta said. “So you found this old recipe and—”
“Impossible!” interrupted Karl. “Igró pir no longer exists. If the recipe had been saved, people would have been using it in war.”
“Karl is right. The recipe was lost with the demise of the Byzantine Empire. Until recently no one knew how to make igró pir. Until the day someone invented it anew.”
“Leonardo da Vinci,” exclaimed Karl. “You got the recipe from Leonardo.”
“Yes. He reinvented igró pir. His mixture is probably even deadlier than Kallinikos’s original recipe. If it is manufactured correctly, it can even be lit with water and cannot be put out.” Johann gave a dry laugh. “Apparently, Leonardo also toyed with the thought of producing an invisible deadly gas. Thankfully, he didn’t succeed. But he soon realized that with igró pir he had invented a weapon that had the power to send the world into chaos. In the wrong hands, he knew, Greek fire could topple whole empires and create dark imperia. And that is not all.” He paused before he went on, with a grim expression on his face. “Leonardo must have sensed that someone profoundly evil was after his recipe. Someone he couldn’t fight. Someone who sent me to Cloux to find the secret for him—without me knowing that I was.”
“Tonio del Moravia,” said Greta.
Johann nodded. “Now I know that this was his plan. I assume that he blackmailed Agrippa or made a pact with him also, so that Agrippa would send us to Cloux to visit Leonardo. Tonio wanted me to find the recipe for him.”
Karl stared at him, feeling a small pang in his heart. “A setup, right from the start?” Once again the doctor hadn’t told him a thing; as always, there had been secrets that Faust didn’t share with anyone. Not even with Karl.
“I believe that’s how it was.” Johann wiped his sooty hands on his filthy coat. “Tonio sent me the disease and, through Agrippa, slipped me the clue that only Leonardo could heal me. He knew that I would never have done him such a favor voluntarily! But he was counting on my curiosity and hoped that Leonardo would open up to
