Adrian continued spitting questions at her, his tone more flustered, but Hailey wasn’t listening. She didn’t care about the professor. She was focused on that urn, her mind churning through what she knew. The copper book and the eagle were somehow connected. The eagle had been molded in 1814 and had two prescience symbols engraved above its claws. Those symbols had enabled her to reveal the hidden letters in the book. The letters were encrypted—except for a line from Newton, translated into French above a picture of this urn—which had been placed here, with a massive obelisk built on top of it, the cornerstone laid by a French Revolutionary Wars hero.

She believed that all of it was somehow significant. But her mind kept coming back to Newton. He hadn’t been chosen by accident.

Nick burst back in through the doorway, breathing hard, and held out a plastic water bottle. Hailey took it from him. She opened the top and spilled out just enough so that the bottle was a little less firm in her hands. Then she squeezed the plastic with her fingers, adding crinkles, angles, and curves.

Both Nick and Adrian were staring at her as she held the bottle in one hand, then opened the mirror and stepped a foot back. Extending her arm, she moved the mirror until she found a spot where the soft glow from outside reached into the monument.

The mirror flashed in the stream of sunlight.

“What do you do,” she asked, as she played with the angle of the mirror, flashing that sunlight into the elevator shaft, “if you want to preserve a secret for a very long time?”

“You hide it in a monument?” Nick tried.

Hailey moved her wrist a few more inches. The light was now flashing against the replica column inside.

“I think it’s the other way around. The engraved symbols on the eagle must have coincided with or come after the book. The eagle was molded in 1814. The memorial to Warren was erected by the Masons in 1775—just a couple months after Paul Revere’s ride. But it wasn’t until 1825 that it was moved here, and then the obelisk was built on top of it.”

She shifted the mirror another inch, playing the reflected light up the column—until it reached the gilded urn. The urn flashed in the light. She could see the little imperfections more clearly, now. Errors of the artificer.

“You want something to stick around a long time, you make it unique, and you make it sacred. Maybe you build a monument over it that nobody’s ever going to knock down. Nick, come over here—I need your help.”

Nick moved next to her, and she handed him the creased and crinkled water bottle.