PrologueTHE LOOP There came a time when Aaron Hayes realized that there’d been no loop at all, even though on dozens of occasions it had appeared as if there were. He’d seen signs of a loop with his own eyes, but he’d also seen evidence to the contrary. And although this contrary evidence had presented itself only once, he believed that even a solitary exception disproved a rule. He held firm to this even when his scientific mind conjured doubt, for everything he was about to do depended on it—the nonexistence of fate, the preeminence of free will, the assured absence of a loop. Behind him stood eighty years of a long life, much of it spent in solitude. Ahead of him: his last and greatest endeavor. Success would retroactively change his life and, with luck, erase its most tragic consequences, bringing health to sickness, knowledge to ignorance, and justice to wickedness. It would change everything. He recalled a day from his past—the only time he’d ever felt real doubt about a decision. In that moment, he’d imagined proverbial signposts all around him, pointing in countless directions, toward a myriad of possibilities and outcomes. But as he’d looked upon those signs, he’d found only one that was decipherable. Readable. Only one he could have followed at the time. He thought it a sign of fate. Now, he saw how he’d been wrong. And how his doubt had been right. Aaron chased away the memory and looked around. He sat alone in a tidy room near the back of his home. Beside him, through a large floor-to-ceiling window, he could see the dark, gentle curve of a nearby hillside. Above glittered a clear starry night and a crescent moon, bright but waning. He then caught his own reflection in the glass. Though he had aged, time had been kind. It had taken his youth, but it hadn’t blurred his focus or dulled his acuity. His graying features betrayed his years, but at his core and in his character still lived the soul of a man half his age. He offered his reflection a kind smile. “You’ve done it, Methuselah,” he said, using a playful epithet for himself that had been given to him in jest when he was young. He’d often laughed at that moniker. But it was an undeniable truth now, not just the echo of the coy flirtation of the man who’d given it to him. Dozens of etched glass data cubes, each the size and shape of a six-sided die, lay scattered on the polished wooden desk in front of him. Above the table hung a wide computer monitor—a thin pane of opaque, shatterproof glass with polished edges, but no notable design features. The room was otherwise unembellished, for it had long served only one purpose: the study of a small, enigmatic device that Aaron called “the needle.” The needle had been the source of his angst, the leading antagonist of his life, but tonight it would be his salvation. It sat before him, resting on a compact computer tablet similar in style to the monitor, an opaque glass panel the size of his hand. The needle itself was a cylindrical object, the length and thickness of a small pen and finely tapered at both ends. It had a seamless, satiny blue skin that appeared to undulate as if a stellar nebula swirled within. Embedded on one side of the device were two small gold lights, set three centimeters apart. Flanking them were two series of numbers, broken by decimal points. The needle had an electric quality overall, its features apparently projected on its glossy surface like images on a screen, but so fine and detailed that the shapes themselves seemed real and material. Aaron hovered over the needle with an air of victory. It had been a mystery for too long. Mastering its power had been his purpose. He’d always known its function, but how to make it work had eluded him. Now, after years of experimentation and revelation, he understood. All that remained was to power it up one last time and set his plan into motion.