“If we’re going to discover that,” Gray said, “we’ll need to find that third key. But where do we begin to look? There’s no angelic script anywhere.”

“Maybe no angelic script that we could see with the naked eye,” Vigor added pointedly.

Gray nodded his understanding. He twisted around to his pack and began fishing through it. “I brought a UV light. In case we ran into any more glowing obelisks.”

Balthazar dimmed the lights. Gray ran the UV over every artifact. Even the shard of broken clay brick.

“Nothing,” he finally admitted.

Dead end.

Gray’s frustration had stretched to the tautness of a piano wire. He gave up any hope on his original plan, though it had been a long shot.

“We can’t wait any longer,” he finally admitted, checking his watch. “We have to get into hiding. Let’s gather this all together. Find a place to hole up.”

They had spent the last five minutes racking their brains, searching for some clue as to where to seek the third key. Vigor attempted to decipher a hidden meaning in the text, going over it again. Balthazar had studied all surfaces of the golden paitzu. Everyone agreed that the crude line circling the single angelic letter had to be significant, but no one could guess what it might be.

Vigor sighed and began rolling up the scroll. “The answer must be here. Seichan said the Guild’s copy mentioned how each key would lead to the next one. We just have to figure out what we’re missing later.”

Gray gathered up the last remaining artifact: the chunk of the brick itself. He tapped the plaster on the outside of the chunk. “Could there be some significance to the brick being plastered in purple? I’m assuming the false brick could have been any number of colors. They had the entire dome’s palette to choose from.”

Vigor barely seemed to hear him as he tucked the scroll back into its bronze tube. Still, he mumbled aloud. “Purple is the color of royalty or divinity.”

Gray nodded. Grabbing his backpack, he shoved the chunk inside. His thumb ran over the thick blue glaze on the opposite side. Gray remembered the inside of the brick had felt glassy.

“Blue,” he whispered aloud. “Blue and royalty.”

Then it came to him.

Of course.

Vigor realized it at the same time and sprang straighter. “The Blue Princess!”

Balthazar slid the gold paitzu over to Gray to pack away. “You’re talking about Kokejin. The young Mongol woman who traveled with Marco.”

Vigor nodded. “She gained her nickname because her name translates as sky blue.”

“But what’s the significance of her reference here?” Gray asked.

“Let’s backtrack,” Vigor said, ticking off on his fingers. “The first key was at the Vatican, in Italy, where Marco ended his journey. A major milestone. Following Polo’s route backward, we come to the next milestone here, in Istanbul, where Marco crossed from Asia and stepped for the first time back into Europe.”

“And if we trace Marco’s route further back…” Gray said.

“The next major milestone would be at the site where Marco completed the task set to him by Kublai Khan, the whole reason for the journey: to bring Kokejin to Persia.”

“But where exactly in Persia?” Gray asked.

“Hormuz,” Balthazar answered. “In southern Iran. The island of Hormuz lies at the mouth of the Persian Gulf.”

Gray glanced to the table. An island. He picked up the golden paitzu and traced the line encircling around the angelic symbol. “Could this be a crude map of that island?”

“Let’s check,” Vigor said, and stood up. He crossed over to the curator’s old illuminated map on the wall.

Gray joined him.

Vigor pointed to a small island near the bottom of the Persian Gulf, close to the mainland of Iran. It bore the same rounded shape with a distinct teardrop tip. It was almost an exact match to the drawing around the gold glyph.

“We found it,” Gray said, his breath quickening in anticipation. “We know where we have to go next.”

And that meant his plan could still work.

“But what about Nasser?” Vigor asked.

“I haven’t forgotten about him.” Gray faced the monsignor and gripped his shoulder. “The first key. I want you to give it to Balthazar.”

Vigor frowned. “Why?”

“In case anything goes wrong here, we can’t let Nasser get ahold of it. We’ll present the second key we found here as the first one. Nasser can’t know that you found a key in the Vatican.” Gray stared between them. “I assume you two kept it between yourselves.”

Both men nodded.

Good.

Still, Vigor’s frown had not dimmed. “Surely when Nasser gets here, he’ll search Balthazar and find the other golden key.”

“Not if Balthazar is already gone,” Gray said. “Like with Kowalski, I doubt Nasser knows your colleague traveled with you. Why would he suspect you came here with the dean of the art history department? By tracking your cell phone, all Nasser knows is that you left to meet us. We’ll use that to our advantage. We’ll send Balthazar with everything he needs to know. Out to Seichan. Along with Kowalski, the three of them can get a jump start and head over to the island of Hormuz. It will be up to them to find the last key. Once Nasser arrives here, we’ll have to stall the bastard for as long as possible. But for the sake of my parents, we may have to eventually send him on the right path.”

“Where hopefully Seichan will have already found the last key,” Vigor said.

“Then we’ll have something to bargain with,” Gray said.

Still, Gray knew all of these plans hinged on one last hope.

That Painter found a way to free his parents.

And of course, that Gray had not made any gross miscalculations himself.

Seichan waited inside the hotel room across from Hagia Sophia’s west entrance. She sat by the fifth-floor window. Her cheek rested against the stock of her Heckler & Koch PSG1 sniper rifle. She stared down its telescopic sight, focused on the plaza in front of the church.

She had watched the police come and go, stopping only briefly.

What had happened?

Behind her, Kowalski lay stretched on the bed, chewing on olives and cleaning five hand pistols and a 5.56 mm NATO A-91 assault rifle.

They had gone shopping, stocking up on the essentials.

Kowalski whistled around an olive pit as he worked. It was getting on her nerves as she kept her post. But at least he knew his armaments.

From her vantage, Seichan had a clear view of the street, park, and plaza. She watched for anyone taking an inordinate interest in the church, more than the typical flash-and-go tourist. She also watched for any telltale sign of someone carting heavy weaponry.

So far so good. Either that or she was losing her edge.

Through her telescopic sight, she watched everyone leaving or entering through the western Imperial Doors of Hagia Sophia. She adjusted the focal length to get a clear view of the faces. She kept inventory. To see if any of the same faces came and went, indicating someone who was canvassing the place.

She wanted to know where as many of the hostiles were positioned as possible.

In case an assault proved necessary.

So far nothing. It made no sense.

Where were Nasser’s men? They should have been here by now, taking up positions. The Guild had many resources and assets in Istanbul. The supply of arms behind her was proof enough of that. Or was Nasser operating lean? Keeping his manpower to a minimum? It was easier to blend one or two men into the scenery than a half dozen.

Still, Seichan wasn’t buying it.

“Something’s wrong,” she muttered, bobbling her view.

What was his game?

She concentrated back on her duty. A large man exited the church, crossing in large strides, not attempting to hide. Seichan focused on him, bringing up his bearded face.