The police officer leapt forward into the monument and jogged to his left, toward the stairs. Zack followed Marsh after him.

Once they were past the entrance, the air got a little cooler, a lot darker, and a hell of a lot louder. Caught in the blare of that alarm and the narrow walls of the obelisk, Zack had a moment of sudden claustrophobia; he’d never loved small, enclosed spaces, but he’d been in enough hidden art vaults and aging, guarded museum chambers to know how to control the feeling. Once it had passed, he let Marsh direct him to the bottom of the winding, ascending steps. The pounding of feet coming down toward them was louder, now, and growing by the second.

“You take the left side; I’ll take the right. It’s very narrow, so it’s mostly going to be one or two at a time coming through. We go slow, and we lock eyes with everyone who passes. Got it?”

Marsh had the snaps of his holster open now, and his fingers were on the grip of his .38.

“There could be kids in here,” Zack said.

“I’ll aim high.”

Before Zack could respond, the first pair of tourists came jogging down toward them around the curve of the stairs. Both looked to be in their mid-fifties and were breathing hard. Zack moved aside to let them through, but Marsh was really giving them a once-over. He might have been a thug, but at least he was thorough.

Once they’d passed, another group came around the curve—and Zack could see the stairwell behind them was crowded with people now, all jumbling together as they rushed down. The blare of the fire alarm was so loud in the confined space it made it hard not to panic, and the tour group was almost one on top of the other as they pushed their way down toward the entrance.

Marsh was cursing under his breath as he continued to try to look everyone over while not blockading their path; Zack, for his part, was quickly parsing the crowd by height, weight, and age. Some he could rule out immediately. Others, he had to look a little closer. The few right in front of him were older—two of them at least sixty, wearing matching red sweaters—but behind them, higher on the stairs, he caught a glimpse of a woman who fit the right age. At that distance and in the darkness her features and hair didn’t seem right, and she was wearing glasses, but maybe as she got closer—

Suddenly Marsh was grabbing at him, cell phone jammed against his ear.

“It’s Karp—he made it to the top. Guess what? They’re not coming down the stairs.”

“What do you mean?”

“Follow me,” Marsh snarled, and he barreled upward, pushing his compact body through the rush of tourists coming down.