Ocean below, Sun above; blinding if he looked too closely so he stayed on the straight path, watching always ahead, never off to the side—or behind. The air was clearer than the most beautiful day on the Iberian coast. Sunlight shimmered in the air as he had watched it shimmer countless times on the Mediterranean. Each point of light was pleasant but a siren calling him away from his journey, and if he left the sea he knew he would be dashed on the rocks. There was only one path for Marcus Varrus Trogia, who flew over Rome now, and the Oceanus itself would part for him . . . 

Three Rivers pulled away with a sharp gasp.

"You will not die," she whispered. "Not tonight. If you are willing to die, you will live."

"What did you do to me, woman?" Trogia threw off his blankets and grabbed his tunic. But he felt energy and focus returning— perhaps moreso than any time in his life.

"You must return to Rome," her words tumbled in a rush. "You have landed here in the first gale of a storm."

He gritted his teeth. "And how would you have me escape? In the dark, in unknown territory, when Quintillius is certain I will flee?"

Her eyes turned the dark gray of thunderheads. "I shared your visions, Roman. Our first was the mountains we could not see past. In our second you flew back to Rome and I flew with you. I am named for three journeys my mother's dreams said I would take. Home, with the Lakota. Here to the Ambrosians. And now, with you to your home. If we—"

"We?"

"If we do not, your people and my people will all die. Maybe not next year, or the year after that, but they will be thrown against the cliffs until nothing is left of them."

Fully clothed again, Marcus straightened and stared down his nose at her. "Even if I could escape, twelve of my men are still imprisoned."

"I will find their freedom, and then have your trust. As for you, your eyes have cleared. You know where to go next. I will meet you at the trailhead where you entered."

"I—" he started, but cut himself off. Yes, he did know what to do next.

He wanted to cripple Terra Ambrosia. His first idea was to kill Quintillius, but no—that was a wrong thought born before his eyes opened. Someone else would just step into Quintillius' sandals; there were always men waiting to march their own way into power.

But there was one other.

"You coming to see my master?"

Nikolaos Azanties' riverside house, in sight of the two ungainly metal ships, was unguarded except for one figure: the Greek's surly apprentice, Marcion. Marcus inwardly flinched at the dishonor of holding his sword ready to cut the boy down, but the blade never wavered.

"Move aside and stay quiet," Marcus said, "and live."

"You're going to run tonight?" Marcion pressed. "Take me with you and I'll tell you everything you need to know."

"I have no need of children."

Marcion puffed up his chest. "I know you want to kill the old man. Well, so do I. But I know how to build weapons and ironships. I know where he keeps his notes and what books to grab. If you don't take me it'll be years before you know how to do what he's done, and by then the Ambrosians'll be too far ahead to catch."

"Ambrosians? And what are you, Marcion? You're too young to have sailed on the colony fleet."

"I'm Roman, general. Take me home and I'll work for you the rest of my life."

The library was pitch black but Marcion knew the layout well enough to find a lamp in the darkness. "His notes are locked in that cabinet," Marcion whispered, piling books into his arms, "but he keeps his key in a secret drawer that pops out the side. You'll want all of Hero of Alexandria's works—his treatises on pneumatics and hydraulics and mechanics. And those over there, Archimedes, that math book by Al-Khwarizmi, The Principles of Steam Power by Ibn Athir—"

But Marcus fixated on the hunched silhouette drawing circles in the dust on a drafting table in a far corner. He heard Marcion's running footsteps and the slamming door.

Marcus pointed his sword at the old man. "I offer you your life, Azanties," he said, "if you'll come with me."

"Hostage?"

"What you built for these Ambrosians you'll build for Rome. You will live, and you will be a hero to the Empire. I can promise you this. But you will not be allowed to continue working for the traitor."

"You will not allow it, ay?" Azanties rubbed his mouth as if that could erase his chuckling. "You may as well use that sword, Trogia. Even if I wished to go I am an old, old man. I would never survive the oceanic crossing. Besides, Rome doesn't want me."

He traced another circle in the dust, then gazed up at Marcus, never once eyeing the blade. "You've barely seen what we've done here, Marcus. Yes, you've seen some of the most impressive inventions with military applications, of course. But not the pumps, or the engines, or—" He waved at his table, and Marcus recognized drawings of the miniature gears of his own pocket watch. "Quite lovely, though the engraving betrayed its origin in Persia, not Rome."

Marcus realized there was a draft in the closed windowless room. He looked into the breeze to see a long, thin hole carved into the wall, behind which he heard the strange pumping sound. Air circulation pumps, he remembered, and wondered what else this man could turn against Rome.

"I will ask you no further, Greek," Marcus told him. "You have no other choices."

"But you do! All of this we have done in a single generation. Do you know how, Trogia? Because in this new world we started anew and anything is possible. Rome . . .  ah, Rome was never an empire of inventors. Almost everything it has it stole from other nations, and then those nations stopped inventing when Rome claimed them. And the Eastern Empire lost its science four centuries ago when Justinian the Lesser closed the great schools. Drove the scholars out, only to have Persia and the Arabians welcome them. So Constantinopolis is stultified, and Rome is sterile. And Persia rises again."

He traced lines through his circles. Marcus recognized the drawings as some sort of mathematical proof, though he knew not what. Thunder shook Azanties' library before he could reply, one clap, then another.

"Ah, Marcion," the old man sighed. "I imagine we have just heard the deaths of Aphrodite and Artemis, thanks no doubt to well-placed torches in their powder stores. A pity, but they can be rebuilt."

Marcus shook his head. "Even when you're dead, Azanties?" I could burn this entire library now . . .  the Ambrosians would believe the steamship fires started it . . .  But why would I care what they believe?

Now the old man didn't bother hiding his chuckling. "Is that what you think, Trogia? That killing me will put an end to all of this? No. Everyone is free to pursue what they will. Even the children are taught how a crank builds an engine and a rotating crank builds a steamship. And the machines have become necessary with no slaves . . .  " He leaned toward Marcus with eyes glittering in the non-sputtering lamplight. "Freedom, Trogia. All this in a generation because of freedom. That is why we hid from Rome, why we kept this land to ourselves, and why killing me will do you no good.

"Do you know the story of Archimedes, general? The founding father of real science. He was born in Syracuse, a free city, though the Romans took it when he was old. His machines and burning mirrors did terrible damage to the Roman fleet. And yet, and yet, the Roman commander Marcellus—Marcus Marcellus—knew Archimedes' genius and wanted the old fellow spared. But one soldier, one ignorant soldier, stumbled across Archimedes in his library. The stories claim that Archimedes was oblivious to the fall of his city, but I have never believed that. I believe he knew exactly what he was doing, even when he asked the soldier not to interrupt the new theorems he worked on—as Archimedes said, not to disturb his circles."

"The soldier killed Archimedes," Marcus remembered. "And Syracuse fell to the Romans. But there was never another Archimedes."

"Not under Rome's dull iron hand." Azanties turned away, tracing in the dust. "Don't disturb my circles, general."