Zack followed, pushing after him. The tunnel grew darker as they moved up from the bottom, and within a few steps it was hard to see anything. If any of the people he was pushing past were Nick and Hailey, he would have had to have gotten right in their faces to have seen—but Marsh was moving like a man possessed, shouting for Zack to keep up. Within a few minutes they’d passed the tourists, and now it was just the two of them churning up the spiral staircase.

By the time they reached the top, Zack’s breaths were coming in bursts. He pushed himself out into the observation deck a foot behind Marsh, who now had his gun drawn and out in front of him.

The detective’s square head swiveled on his thick neck, back and forth, but it was obvious—the fugitives were nowhere to be seen. The only two people in the room were Karp and a uniformed park ranger. Karp was down on one knee, in front of what looked to be a circular opening cut into the granite floor. A grate that had apparently covered the opening was bent halfway back, a chisel of some sort on the ground next to it. The BPD officer was leaning into the opening, while the park ranger aimed a flashlight over his shoulder.

“I think I see one of them,” the officer hissed back at them, “about ten yards down. Wearing denim, hanging from one of the rungs.”

Marsh rushed forward to take a look.

“What the hell is this?” he snarled.

“The nation’s first passenger elevator,” the park ranger answered, a little too proudly. “Well, now it’s just the shaft. But in 1843—”

“Shut the hell up, Ranger Smith, and get your ass down to wherever that shaft opens up. Now!”

The park ranger rushed past Zack and hit the stairway at full speed. Marsh was still next to Karp at the edge of the shaft.

“How did this happen?”

“The ranger said after the alarm went off, he quickly corralled the tourists and led them into the stairwell. He’d gotten a few yards down the steps when he’d heard noises from up above. He’d come back up to find this. They must have used the chisel to get the grate loose.”

Marsh shook his head.

“You still think we’re dealing with a couple of geniuses here, Lindsy? It’s a long way down. From fish in a barrel to rats in a hole.”