After the night in the forge, he had again done his best to avoid Cyprian. Nazira had few useful contacts left; Helen’s disgrace at being associated with poor impaled Coco left her a pariah, and Nazira was swept along in that wake. Most of her time was spent trying to find food and delivering it to those in need. Radu never asked what the latter accomplished. He understood the need to extend kindness even as the very act devoured the soul with guilt. He understood the desire for penance, as well.

When Radu made it home to sleep, he and Nazira lay in the bed, not touching, not talking. Side by side, and alone together. The only thing Radu was certain of anymore in the sea of endless smoke was that Nazira would make it out alive. Everything else was negotiable.

On May nineteenth, the bells of the city jangled out their now-familiar call to the wall. Panic! they said. Death! they said. Destruction! they said. They were no longer instruments of worship, only proclaimers of doom.

Radu trudged past the Hagia Sophia. A sharp tug on his shirt startled him. He turned to find Amal. “I do not have anything for him,” Radu said.

Amal shook his head. “He has a message for you.”

Radu’s weary heart stepped up its pace. Mehmed! His Mehmed. “Yes?”

“He says to stay away from the walls today. Find somewhere else to be.”

Radu did not know whether to laugh in delight or cry in relief. Mehmed remembered him—and cared whether or not he was safe. “Why?”

Amal shrugged. “That is the message.”

“Tell him thank you. Tell him—” Tell him I miss him. Tell him I wish things could go back to how they were. Tell him I am terrified they never can. Tell him even if they could, I do not know if I will ever be satisfied with it again. “Tell him my thoughts and prayers are with him.”

Amal nodded, then held out his hand as though begging. Radu dug free a single coin and placed it in the boy’s palm.

Radu turned to go back home, happy he could at least report to Nazira that Mehmed thought of them and had sent a warning. And then he remembered: Cyprian was already at the wall.

The wall Mehmed thought was dangerous enough it merited risking sending a message.

Radu could go home. He could wait and see what happened. He could stand at the window, watching for Cyprian. And if Cyprian did not return …

Radu ran for the wall. He would think of some reason, some excuse to pull Cyprian away. He did not question why it was worth the risk. He simply knew he had to.

When he got there, though, he stopped in shock. There were towers on the other side of the wall. Made of wood, they were covered in sheets of metal and leather hides to protect them from fire and arrows. Huge wheels stuck out from their bases. And they were making their way toward the city.

Where Mehmed had been keeping the towers was a mystery. No one around Radu knew where they had come from or when they had appeared. But their purpose was already being served. As the towers moved forward, the shielded men within them threw dirt and rocks and bushes into the fosse. Slowly but surely they were filling up the protective ditch.

Radu hurried past a line of archers, desperate to find Cyprian. Mehmed had not wanted him here, and he saw why now. The walls would fall today.

The archers shot burning arrows, but they bounced harmlessly off the towers’ shielded exteriors. Small cannons were fired to little effect. The towers carried on without pause. Giustiniani pushed his way to the center of the wall, a few men down from where Radu crouched behind barrels. A constant barrage of arrows flew at the wall, preventing any concerted counterattack.

“What new hell is this?” Giustiniani said, peering between barrels. He noticed Radu and crawled over to him, gesturing toward the towers. “Did you know he had these?”

Radu shook his head, leaning back against the barrels, unable to face the towers.

All his previous anger at Mehmed had fallen away, like an arrow bouncing off the armor Mehmed’s message had supplied. But Mehmed protecting him and Mehmed trusting him were two different things. The towers had to have been in the works since the beginning. And Mehmed had never breathed a word about them to Radu.

Which meant one of two things: either Mehmed did not trust him, or Mehmed had deliberately withheld information because he had been looking for a way to get Radu into the city from the very beginning, and he had suspected Radu would be caught and tortured.

Even with the armor of Mehmed’s warning, either option broke Radu’s battered heart.

By nightfall the ditches were filled enough for the towers to cross them. Their progress was as slow and inevitable as the passage of the sun. As near as anyone could tell, men in the bottom pushed, inching them forward. The rain of arrows from the towers had not stopped. No counterattack could be launched, no run on the towers was possible. They crept forward at an agonizing pace, slowly bringing the city’s doom. And still Radu had not found Cyprian. At this point he could not leave—because he did not have his friend, and because it would look as though he was running away.

Someone rode across the space between the walls on a horse pulling a heavily laden cart.

“Giustiniani!”

It was Cyprian. Radu perked up. The city was going to fall, but Cyprian was here! Radu could get him out, and they could get to Nazira and flee. Radu crouched, running along the wall to the ladder, then climbed down.

Cyprian was standing in the cart, arrows falling around him as he pushed a barrel off the end. Radu grabbed a discarded shield and ran forward, climbing on next to Cyprian and covering him while he worked. “We need to go!” Radu shouted.

“Almost finished!” An arrow thunked against the shield over their heads. Cyprian paused, giving Radu that smile that changed his whole face. “Well, that is another life I owe you. One of these days you will have to determine how I can repay you.”

“What is this?” Radu asked as a few other men who had come to help lifted barrels down.

“Gunpowder.”

“The cannons are too small to do enough damage to the towers.”

Cyprian’s grin shifted to something less warm but more appropriate to their surroundings. “Not for the cannons. Get these on the wall!” he shouted.

Radu jumped down, still shielding Cyprian as he directed the men. He kept looking toward the gate, wondering how he could get himself and Cyprian out. Meanwhile, Cyprian continued, oblivious to Radu’s desperation. It was no small task leveraging the heavy barrels up the narrow ladders. They managed awkwardly, losing one man to an arrow. Radu followed Cyprian as they rolled the barrels along until they were positioned directly in front of the tower. Maybe if he helped Cyprian accomplish whatever he was doing, Radu could trick him into leaving.

Giustiniani gestured with concern. “This is nearly all the gunpowder we have left.”

“It is doing us no good in the cannons,” Cyprian said. “This is our best chance.”

“But we do not have enough to take out all the towers. There are several more.”

“The sultan does not know that, does he?”

Understanding dawned on Radu as Cyprian worked long fuses into the tops of the barrels. “You are going to blow up the towers.” Radu laughed, his throat hoarse from exhaustion and smoke. It was exactly what Lada would have done. He should have thought of it himself.

No. He was not actually on this side. Radu tapped his head against the stones beside him, trying to knock some sense into himself. He should do something to prevent it. But he was trapped. He could not do anything for Mehmed, and he could not do anything to risk Cyprian’s life.

Cyprian patted his vest, swearing. “I do not have a flint.”

Radu held out his own. When Cyprian’s fingers met his, there was a spark unrelated to the flint. Radu swallowed the mess of emotions blocking his throat and his breath.

Cyprian grinned at him, then struck the flint and lit the fuse. “If it bursts open when it hits the ground, we are blowing ourselves up.”

Radu shrugged, sitting back. Perhaps that would be a kindness at this point. “At least I will have good company in hell.”

Cyprian laughed. Giustiniani glared at them both. “On three,” Cyprian said. The two other barrels were a few feet away. “One … two … three!”

Radu and Cyprian pushed the barrel up and over the wall while other soldiers did the same with theirs. They braced for an explosion, but none came. They peered over, holding their breath and watching as the barrels tumbled and rolled away from the wall and toward the tower. Giustiniani’s veered too far to the right, lodging in debris. The third barrel lost momentum halfway there. But Cyprian’s kept going, rolling right to the base of the tower.