Then a word popped out at her. A single word. Stern. German for star and one of the words that started this whole adventure. From then on, she couldn't draw her mind away from the text. Turning back to the first page, she began to translate, haltingly at first, then with more vigor as she grew accustomed to the old script.

I, Hans Novak, aged thirteen years, four months, eight days, here set down these words as Magister Nicolaus Copernicus has told them to me and as I myself have lived them.

The words swept over her, drawing her back to a time and place far away from their own.

To begin, I must record what happened before my humble appearance in the Magister's story.

Nicolaus Copernicus was born in 1473 in the town of Toru n, Poland, under stars that proclaimed him a visionary and a rebel.

How true were those stars!

At the age of eighteen, already on the path that would later crown him with glory, Nicolaus attended the great University in Krakow.

He studied hard. I know that, of course, as everyone must have, from his brilliance. He became a canon in law at Bologna. There he met the sword master, Achille Marozzo. At Via C Selvatica, he learned the art of the blade- "I knew it!" Darrell slapped his hand on the table. "He was right here! In this place. Man. Go on, Becca. Sorry."

Before he returned home to Poland, Nicolaus was given a gift from Achille. He related it to me thus: "What is this?" Nicolaus said.

Achille laughed. "A master sword for a master swordsman! It is unlike any that I have forged so far. First you must name it."

Nicolaus drew out a magnificent broadsword. "Himmelklinge," he said. "Sky Blade."

Achille approved, handing him a second gift. "To go with it, a dueling dagger, a prototype of my own design."

"Its blade undulates like the Baltic Sea," Nicolaus said.

Achille smiled. "May they both serve you well and protect you."

"He's talking about this dagger," said Wade, holding it under the lamplight. "This actually belonged to Copernicus. Keep going."

"Uh . . ." she flipped a page. "There are several pages in, I don't know, maybe Polish? I'll have to skip them for now. Here."

I enter the story in Frauenberg, called Frombork, on the shores of the Baltic. It is the thirteenth night of the second month of the year 1514. Because I can wield a pen, I am sent by the Bishop to assist the Magister with his work.

I arrive after dusk.

The night is cold, clear. The moon is a silver sphere rising aloft over the fir trees. The sky is sapphire black.

"And I'm totally there," Lily whispered, closing her eyes.

"Do you love the stars?" the Magister asks as we stand atop his tower.

"I do," I tell him. "Though I know so little about them."

Copernicus shakes his head. "I look to the heavens, Hans, I work its numbers incessantly, but the teachings are . . . incorrect. The sun and stars, the planets, do not move as we were taught. I must know more!"

Becca paused. Were there noises from the fencing school? Faint sounds? She listened. No, she thought. It's nothing. Keep going.

Then comes the fateful day when a knock comes on the door. Nicolaus leaps down the stairs. "It has arrived!"

It is a ratty old scroll, said to be the secret writing of the great second-century astronomer Ptolemy, author of the infamous Almagest.

"I know about him," Wade said. "Ptolemy was the first to catalog the constellations in any kind of reasonable order. He found forty-eight of them. Dad taught them to me. They're on my star map."

"Ptolemy," Nicolaus says, "was as clever as you and I put together, Hans. This scroll describes astounding astronomical events visible only from the south. Hans, we must go!"

And so, under cover of night and deception, we lock up the Frombork tower and ride the high road south.

Becca paused to breathe slowly. "A journey south from Poland. But for what?"

"Keep reading," said Lily. "Please."

March 17, 1514. Following Ptolemy's scroll, Nicolaus and I undertake a nearly fatal voyage to . . .

"It gets all garbled here with some kind of code we haven't seen yet," Becca said. "It'll take work to figure it out. I'll skip it for now."

. . . where he uses mathematical calculations and the positions of the stars to locate an ancient device first built by Ptolemy himself.

"It is for this," he says, "that we have risked our lives."

"Device? What kind of ancient device?" asked Lily. "Really, that's all it says? This is so not helpful."

Becca was stumbling over words she didn't know the meaning of, but they weren't the only problem. There were obvious astronomical calculations, passages that looked like primitive algebraic equations, more strange drawings.

"Does anybody else hear sounds from upstairs?" said Darrell.

They listened. Something fell, clattered to the floor. Then quiet.

"Keep going," Lily said.

Becca flipped over another three pages of coded script. "So that's followed by another screwy part."

For days Nicolaus studies the device. "Ptolemy had a vision, but his device was doomed to fail. Ours shall not."

On the island, Nicolaus builds, he steals from this and that. What he cannot find, he forges with his own hands. He invents and reinvents.

Then one evening, "Ptolemy's dream is now complete!"

Soon, the long-promised celestial event occurs . . .

"Something about an explosion of light," Becca said.

Nicolaus positions himself in the center of the device and I behind him . . . there is a hole in the sky, and the voyage begins . . .

"A hole in the sky?" Wade jotted it down in his father's journal. "What is he talking about? There's no such thing as . . ."

Becca kept turning pages. "This diary is coded for whole stretches of pages. It's got numbers, letters, and there's the letter V a bunch of times."

Wade turned to her, a frown creasing his forehead. What was going through his mind, she couldn't imagine, but he must have pushed his worry about his father to the side, because then he bit his lip, and his fingers drummed on the table, which she'd seen him do when he was deep in thought. "I wish I had my books. . . ."

She flipped through another several pages, then stopped at a page folded over itself. Delicately, she unfolded it, then gasped.

"What?" said Lily.

And there it was, in a sketch that reminded Becca of the famous drawings by Leonardo da Vinci. Though exactly what it was, she couldn't say.

"That's the device? What in the world is it?" said Darrell. "It looks like a globe or something . . . or . . . is that a chair?"

But she couldn't stop reading, the words coming ever more quickly.

Having laboriously brought the device back to _ , Nicolaus suddenly fears the vast power of the Knights of the Teutonic Order of Ancient Prussia, their murderous Grand Master, Albrecht, and the evil they will do if they possess the device. "It cannot fall into the hands of these men!"

"You don't think . . . I mean . . . is the Teutonic Order still around?" asked Lily. "If Copernicus was afraid of them finding the relics then, could they be the same bunch of people chasing us now? Are the Knights still, you know, a thing?"

Nicolaus makes a decision.

From the machine's giant frame, its grand armature, he will withdraw its twelve constellated parts-without which the device is inoperable.

"I will entrust them to twelve . . . relic keepers . . ."

"Guardians!" I say.

". . . who will vow to hide the device through all time!"

Darrell nodded over and over. "The twelve relics are the twelve parts of the device Copernicus discovered. Plus you know what else? I bet GAC means the Guardians of Something of Copernicus. All we have to figure out is what the thing is that begins with A."

Becca's stomach twisted. "Listen to this."

The relics will be hidden far from one another and all across the world, known and unknown.

"The first relic will be presented to a man above all men who will raise it as if it were his own child," Nicolaus says.

"The relics will be bound, one to another. The first will lead to the last, so that-God forbid it should ever be necessary-the great machine might one day be reassembled.

"This, Hans, this machine, will be my true legacy."

Wade stood and started pacing around the table, murmuring. "And there it is, the relics. The secret society of Guardians to protect them around the world. The first will circle to the last. The machine, whatever it is. The Copernicus Legacy-"

The door suddenly swung wide at the top of the stairs above them. It was Carlo, with a young girl their age, who was dressed and armed for fencing.

"We're being attacked," Carlo said. "The Order has found you again. Take the book. It must be spirited away from here, kept on the move. You cannot escape up these stairs, there is another way-"

"The Order!" Becca said. "So that's who they are?"

"The Teutonic Order killed Bernard Dufort and your friend."

"You know about Heinrich?" said Wade.

Carlo pressed a stone on the wall. A hidden door sprang open. "It was Heinrich who told me to expect a visit to the school. His death caused the lockdown and invoked the Frombork Protocol. This way!"

They hurried into a corridor that inclined downward.

"What's the Frombork-" Darrell started.

"Faster!"

The passage stopped at yet another door. It swung open to reveal an even narrower set of stairs leading down into darkness.

"Do you know anything about my father, Roald Kaplan?" Wade asked. "He was arrested in Berlin by the Order and the police-"

"Arrested is not the word," said Carlo. "And those policemen have other masters. I know little just yet, but I will find out. You must protect yourselves and the book now. Come, hurry!" He hustled them into the next chamber and a passage that sloped upward in a curve.

"You don't really want us to keep Copernicus's diary," said Becca, holding it carefully. "It's priceless."

"The dagger was his, too," said Lily. "I guess you know that."

"Left," said Carlo, drawing them quickly into a further narrow passage. "As valuable as both are, the Guardians have taken an oath far more important. An oath to protect their children and their children's children from the Order's murderous greed and evil. It has been so for centuries."

"Are you a Guardian?" Lily asked.

Carlo bowed his head. "I am one of the many who seek to honor Copernicus's legacy and protect the relics. The road of a Guardian is often one of hiding and sacrifice, and not for everyone. But now, because the Protocol demands the relics be reunited and destroyed, we are all at risk. You included. This way-"

Carlo arrived at a steel door. He paused. "Since 1543 the Frombork Protocol, devised by the Magister himself on his deathbed, has never been invoked. The Order had fallen apart over the centuries after Albrecht's death, and the relics were safe. Then, four years ago, Heinrich Vogel detected strange new patterns of activity. A new master had emerged. With Vogel's death, the inner circle of Guardians has been breached. The Frombork Protocol has begun."

"What can we do now?" Wade asked.

"Go to Rome immediately," Carlo said. "You will find what you need at Five, Via Rasagnole. Remember it. Five, Via Rasagnole. Repeat the name."

The kids did, one by one.

"Five, Via Rasagnole," Carlo said one last time, and then spelled it out, letter by letter, using the Roman numeral V to describe the number, which Becca found odd but helpful.

"Remember this, too. You may not always find the help you seek. Some Guardians will protect their identities to the death. Others do not know their role until events discover it for them. We shall do what we can to hinder the Teutonic Order, and free your father, but your only hope is to stay ahead of them every step of the way."

"Every step of the way to what?" asked Darrell.

"The end of the journey," Carlo said. "The one that began five centuries ago-and started again in Berlin with you!"

More cries came from above. An alarm jangled, then there was the smell of smoke.

"Are those guys seriously the Knights of the Teutonic Order of Ancient Prussia?" asked Lily.