A sound behind them stopped her midsentence. Nick whirled—and to his surprise, saw a familiar figure a half dozen yards down the alley. The professor from the monument—Adrian Jensen—climbing off a bicycle, which he then carefully leaned against the chain-link fence. As Nick and Hailey watched, the man affixed his helmet to the bike, retrieved a leather shoulder bag, and then hurried toward them.

“You kidding me?” Nick said. “You followed us?”

Adrian ignored him, focusing on Hailey.

“The urn at the Bunker Hill Monument—you implied that it was a key to a Jeffersonian cipher?”

“This doesn’t concern you,” Nick said, squaring himself in front of the foppish man. He didn’t think the professor was a threat; if the man had really been following them from the monument, he could have turned them in to the police at any point with a phone call. But his interest was unnerving, and they didn’t need a third wheel—even an overeducated one.

“Everything about this concerns me,” Adrian responded. “That urn is a piece of Revolutionary history, and you’ve found something—”

He stopped, staring toward Hailey’s backpack. The wing of the eagle was still visible above the open zipper, and Adrian’s eyes widened as he seemed to recognize what he was seeing.

“The eagle.”

Hailey glanced at Nick, then shrugged.

“It’s the finial from the Gardner—” she began.

Nick tried to quiet her with a look, but Adrian was already stepping forward.

“No. Paul Revere’s eagle.”

He reached into his shoulder bag and retrieved a thick envelope. With trembling hands, he pulled out a sheaf of pages and turned to what appeared to be the last page. He showed the page to Hailey, and Nick peered down at it from over her shoulder.

The image was strange—black and white and gray, shaded like the negative of a photograph, or something that had been taken by an X-ray machine. But the shape at the center of the image was unmistakable.

“Where is this from?” Hailey asked.

“It’s a radiograph of an original engraving, taken through the wood of a trunk once owned by John Hancock—carried off and hidden by Paul Revere during the battles of Concord and Lexington.”

Nick felt like laughing. But the look on the professor’s face was entirely serious. Paul Revere. John Hancock.

“This engraving is of a mold created by Paul Revere.”

“Paul Revere made Napoleon’s finial eagle?” Nick asked.

“That’s the point. He didn’t make it. To my knowledge—which is, to say, to the best of anyone’s knowledge—there are no Revere eagles. My colleague—Charles—believed this mold was never meant to be fired.”

“Why construct a mold for an eagle you never intended to make?” Nick asked.