“I remember Al-Scarab from my own privateering days,” Piri said. “We fought side by side at both battles of Lepanto a dozen years ago or so, under the flag of my uncle Kemal. No doubt you’ve heard of him?”

“Yes.”

“The Spaniards fought us like tigers, but I didn’t think so much of the Genoese or the Venetians. You’re a Florentine, yourself, aren’t you?”

“Yes.”

“So you’re a landlubber.”

“My family were bankers.”

“On the surface, yes! But something far more noble underneath.”

“As you know, banking does not run in my blood as seafaring does in yours.”

Piri laughed. “Well said!” He sipped his coffee, wincing as he burned his lips. Then he eased himself off his stool and stretched his shoulders, laying down his pen. “And that’s quite enough small talk. I see you’re already looking at the drawings I’m working on. Make any sense of them?”

“I can see they’re not maps.”

“Is it maps you’re after?”

“Yes and no. There is one thing I want to ask you—about the city—before I talk about anything else.”

Piri spread his hands. “Go ahead.”

Ezio took Niccolò Polo’s book, The Secret Crusade, out of his side wallet, and showed it to Piri.

“Interesting,” said the seaman. “Of course I know all about the Polos. Read Marco’s book. Exaggerates a bit, if you ask me.”

“I took this from a Templar at Masyaf. Yusuf knows of it and of its contents.”

“Masyaf? So you have been there.”

“It mentions the five keys to Altaïr’s library. From my reading of it, I see that Altaïr entrusted the keys to Niccolò, and that he brought them here and concealed them.”

“And the Templars know this? So it’s a race against time.”

Ezio nodded. “They’ve already found one, hidden in the cellars of the Topkapi Palace. I need to recover it and find the other four.”

“So—where will you begin?”

“Do you know the location of the Polos’ old trading post here?”

Piri looked at him. “I can tell you exactly where it was. Come over here.” He led the way to where a large, immensely detailed map of Constantinople hung on the wall in a plain gold frame. He peered at it for an instant, then tapped a spot with his index finger. “It’s there. Just to the west of Haghia Sofia. No distance from here. Why? Is there a connection?”

“I have a hunch I need to follow.”

Piri looked at him. “That is a valuable book,” he said, slowly.

“Yes. Very valuable, if I’m right.”

“Well, just make sure it doesn’t fall into the wrong hands.”

He was silent for a long moment, thinking. “Be careful when you find the Polos’ old trading post,” he said. “You may find more than you bargain for there.”

“Does that remark beg a question?”

“If it does, it is a question to which I have no answer. I just ask you to be wary, my friend.”

Ezio hesitated before taking Piri further into his confidence. “I think my quest will start in that place. I am sure there must be something hidden there that will give me my first clue.”

“It is possible,” Piri said, giving nothing away. “But heed my warning.”

Then he brightened, rubbing his hands vigorously, as if to chase away demons. “And now that we’ve settled that matter, what else can I help you with?”

“I’m sure you’ve guessed. I am here on an Assassin mission, perhaps the most important ever, and Yusuf tells me you would be prepared to show me how to make bombs. The special ones you’ve developed here.”

“Ach, that Yusuf has a big mouth.” But Piri looked serious again. “I cannot compromise my position, Ezio. I am Senior Navigator in the Sultan’s Navy, and this is my current project.” He waved his hands at the maps. Then he winked. “The bombs are a sideline. But I like to help my true friends in a just cause.”

“You may rely on my discretion. As I hope I may on yours.”

“Good. Follow me.”

So saying, Piri led the way to the spacious alcove on the west wall. “The bombs are actually part of a naval research project, too,” he continued. “Through my soldiering, I have gained an appreciation for artillery and explosives. And that has served the Assassins well. It gives us an edge.”

He waved his hand at the technical drawings. “I have developed many kinds of bombs, and some are reserved for the use of your Brotherhood alone. As you can see, they are divided into four main categories. Of course, they are expensive, but the Brotherhood has always understood that.”

“Yusuf told me the Assassins here are short of funds.”

“Most good causes usually are,” replied Piri. “But Yusuf is also resourceful. I gather you know how to use these weapons?”

“I had a crash course.”

Piri looked at him levelly. “Good. Well, as Yusuf evidently promised you, if you want to craft your own bombs, I can show you.”

He went round the table and picked up two pieces of strange-looking metal lying on it. Ezio, leaning forward curiously, reached for a third.

“Ah ah ah! Don’t touch that!” warned Piri. “One wrong move and BANG! The building comes down.”

“Are you serious?”

Piri laughed. “The look on your face! Look, I’ll show you.”

For the next few hours, Piri Reis took Ezio through every basic step involved in constructing each kind of bomb and the materials involved.

Ezio learned that each bomb contained the fundamental ingredient of gunpowder, but that not all were designed to be lethal. He’d already had experience of lethal explosives when attacking Cesare Borgia’s fleet in Valencia four years earlier, and Yusuf had shown him how to use diversionary bombs which created smoke screens, thunderclaps, appalling odors, and apparent pennies from heaven. Piri now demonstrated other applications. Among the bombs with lethal effect were those using coal dust, which added a heavy blasting power to the gunpowder, and fragmentation bombs whose shrapnel killed messily over a wide range. Bombs containing sachets of lambs’ blood spattered their opponents with it, causing them to think they had been wounded, and panicking them. Another type of nonlethal explosive, useful in delaying pursuers, was the caltrop bomb, which showered numbers of twisted-together nails in the path of an oncoming enemy. Perhaps the most unpleasant were the bombs that used either datura powder or deadly nightshade.