“Datura and deadly nightshade are two of what we call the witches’ weeds, along with henbane and mandrake,” Piri explained, his face grave. “I do not like to use them except in cases of great extremity and danger. When exploded in the midst of an enemy, datura causes delirium, deranging the brain, and death. It is perhaps the worst of all. Deadly nightshade produces a poison gas, which is equally lethal.”

“The Templars would not hesitate to use them against us if they could.”

“That is one of the moral paradoxes mankind will wrestle with until the day he becomes truly civilized,” replied Piri. “Is it evil to use evil to combat evil? Is agreeing with that argument merely a simple justification for something none of us should really do?”

“For now,” said Ezio, “there is not leisure to ponder such questions.”

“You’ll find the ingredients for these bombs in locations about the city, which Yusuf will tell you of,” said Piri. “So keep your eyes open and your nose to the ground as you roam the streets.”

Ezio rose to take his leave. Piri extended a walnut brown hand. “Come back whenever you need more help.”

“Ezio shook hands and was unsurprised at the firmness of the grasp.

“I hope we will meet again.”

“Oh,” said Piri with an enigmatic smile. “I have no doubt of it.”

TWENTY-FIVE

Following Piri Reis’s instructions, Ezio made his way through the Bazaar once more, ignoring the insistent blandishments of the traders there, until he reached the quarter west of the enormous bulk of Haghia Sofia. He almost got lost in the labyrinth of streets and alleyways around it but came at last to the spot which, he was sure, Piri had indicated on his map.

A bookshop. And a Venetian name over the door.

He entered and, to his surprise and barely suppressed delight, found himself face-to-face with the young woman he had encountered on his voyage to Constantinople. She greeted him warmly, but he saw immediately that he was merely being welcomed as a potential customer. There was no sign of recognition on her face.

“Buon giorno! Merhaba!” she said, switching automatically from Italian to Turkish. “Please come in.”

She was busying herself among her stock and, in turning, knocked over a pile of books. Ezio saw at a glance that this shop was the antithesis of Piri Reis’s well-ordered studio.

“Ah!” said the woman. “Excuse the clutter. I have not had time to tidy up since my trip.”

“You sailed from Rhodes, no?”

She looked at him in surprise. “Sì. How did you know?”

“We were on the same ship.” He bowed slightly. “My name is Auditore, Ezio.”

“And I am Sofia Sartor. Have we met?”

Ezio smiled. “We have now. May I look around?”

“Prego. Most of my best volumes are in the back, by the way.”

Under the pretext of looking at the books, stacked in apparent chaos on a maze of teetering wooden shelves, Ezio delved deeper into the dark confines of the shop.

“It’s nice to meet another Italian in this district,” Sofia said, following him. “Most of us keep to the Venetian District, and Galata.”

“It’s good to meet you, too. But I thought the war between Venice and the Ottoman Empire would have driven most Italians away. After all, it’s only seven or eight years ago.”

“But Venice kept control of her islands in the White Sea, and everyone came to an arrangement,” she replied. “At least, for the moment.”

“So you stayed?”

She shrugged. “I lived here with my parents when I was a girl. True, when the war was on, we were pushed out, but I always knew I would return.” She hesitated. “Where are you from?”

“Florence.”

“Ah.”

“Is that a problem?”

“No, no. I have met some very nice Florentines.”

“There’s no need to sound so surprised.”

“Forgive me. If you have any questions about the books, just ask.”

“Grazie.”

“There’s even more stock in the rear courtyard if you’re interested.” She looked a little rueful. “More than I seem to be able to sell, to be honest.”

“What took you to Rhodes?”

“The Knights of Rhodes are uneasy. They know the Ottomans haven’t given up the idea of taking the island over. They think it’s only a question of time. Philippe Villiers de L’Isle-Adam was selling off part of their library. So it was a shopping trip, if you like. Not very successful, either. The prices they were asking!”

“De L’Isle-Adam is a good Grand Master and a brave man.”

“Do you know him?”

“Only by repute.”

The woman looked at him as he poked around. “Look, nice as it is to chat with you—are you sure I cannot help? You seem a bit lost.”

Ezio decided to come clean. “I am not really looking to buy anything.”

“Well,” she replied, a touch crisply, “I’m not giving anything away free, Messere.”

“Forgive me. Just bear with me a little longer. I will make it up to you.”

“How?”

“I’m working on that.”

“Well, I must say—”

But Ezio silenced her with a gesture. He had manhandled one bookshelf from the back wall of the covered courtyard. The wall was thicker than the others, he could see that, and he’d noticed a crack in it that wasn’t a crack at all.

It was part of a doorframe, artfully concealed.

“Dio mio!” exclaimed Sofia. “Who put that there?”

“Has anyone ever moved these bookshelves before?”

“Never. They’ve been in place since before my father took over the shop, and before that, it had been in disuse for years—decades, even.”

“I see.” Ezio brushed dust and debris accumulated over what looked like far more than decades away from the doorframe but found no handle or any other means of opening the door. Then he remembered the secret door that led to the vault back in Monteriggioni, at his uncle’s fortress, and felt around for a hidden catch. Before long, the door swung open and inward. Within, steps the width of the wall led downward into blackness.

“This is incredible,” said the woman, peering over Ezio’s shoulder. He smelled the soft scent of her hair, her skin.

“With your permission, I’ll find out where it leads to,” he said firmly.