The Time Roads

The murderer crouched opposite Síomón. His long hair hung in wet tangles over his face. Síomón scrambled to his feet and snatched up the knife. The man did not acknowledge him at all as he poured out a quantity of white powder onto his palm.

Breathless, Síomón watched him swallow the cocaine. The stranger wore his face, with all the differences age would make. Silver threaded the fair golden hair. Lines radiated from his eyes and mouth. The flesh along his jaw drooped slightly. A handsome man just entering middle age.

/> Síomón laid a hand over his own shirt and felt the cocaine packet in his breast pocket. No longer surprised, he too took out the packet, poured out the entire contents, and swallowed them. When the stranger rose and walked out the door, so did he.

Outside, the slums had vanished into a haze. Síomón and his twin walked along a strange path lined with dense green foliage. Above, stars burned like digits of a never-ending number.

They came to an intersection, where a dozen paths curved toward the horizon. Impossible, Síomón thought. The Earth curved, certainly, but the unaided eye could not discern it. He glanced toward one of the branches.

They were nineteen. The hazy sunlight, falling through the leaves, cast green shadows upon Gwen’s face, which had the luminescence of youth.

“The past is not immutable,” she said.

“How?” Síomón demanded. “You’ve not proved your theories.”

“I don’t have to. We prove it by living. Our parents proved it by dying.”

They stood by the sunken gardens, underneath a stand of ornamental trees. The late summer sun glittered upon the pool, and a brilliant haze filled the air, making the trees and foliage beyond appear indistinct. Síomón blinked to clear his vision. Paused. Gwen had gone silent, and he sensed a difference in the air. When he glanced back to his sister, he saw creases beside her eyes and strands of silver in her hair.

Thirty-seven.

David Levi bent over a workbench, delicately twining copper wires onto a perforated board. Maeve stood by a tall desk, writing out columns of numbers.…

Forty-one.

The same room, but a different day. He and Gwen stood over a worktable, which was hidden beneath an enormous sheet of paper. Lines covered the paper in a complex grid of red and black and blue. Green circles marked certain intersections; their distribution made a pattern that Síomón could not quite grasp.

Gwen was speaking in low urgent tones. “I thought Paul could manage. He and I discussed it. I judged the risk acceptable.”

“You’re letting emotion distort your judgment.”

“Not this time,” Gwen insisted. “Look. Forget the ordinary intersections. We’ve already identified the ones that matter. Here—” Her finger hovered above one of the green circles. “And here. And here.”

Seven. Thirteen. Seventeen. Nineteen. Twenty-nine …

“I know that,” Síomón said. “But we have not identified all the permutations of twenty-three. Until we do, the path remains incomplete, and we cannot risk making even one journey.”

“141955329,” Gwen said crisply. “Times two. Exponent 25267. Add one. Ó Dónaill confirmed the latest pair of primes yesterday. He said that true pioneers cannot always wait for absolute knowledge before testing their theories. You used to believe that yourself.”

“In a different time line,” Síomón said. “A safer one.”

“This one is safe.” She jabbed her finger at the intersection marked twenty-three. “David ran the new primes using the same formulae. The results looked promising. Take the route through this intersection, and we have a clear path to the day in question. Alter one conversation—just one—and that balloonist might have known about the high winds. He might have—” She stopped, drew a deep breath. “He would have chosen a different route and avoided the accident. Our parents would have lived.”

“What about the permutations?” Síomón asked softly.

Gwen set her mouth into a thin line. “Close enough.”

“Obviously not.”

Tears brightened her eyes. “Obviously not. Síomón, we were so close, and when Paul volunteered…”

It was Paul Keller who first had the idea of using prime numbers in their work. Li Cheng and Úna Toíbín had researched the formulae they needed, and David Levi had designed and built calculators to speed their computations. Nicolás Ó Cionnaith had alighted upon the inspiration of linking the human brain with the machine. From there, Evan, Maeve, and Ó Dónaill had begun to map out a viable path through the past. But it was Gwen who deduced they could use a combination of numbers and drugs and electricity, just as the old mathematician-conjurors had claimed.

“We can start with cocaine,” she told the others. “And test its effects on varying levels of current.”

The results had proved terrifying. And effective.

We used our madness and our genius, Susanna used to say, and from that we would benefit mankind.