Bell ran for what felt like miles, city block after city block, until he thought he could not run another step, nor lift his boots once more from the grasping mud. And still the man kept running, covering the broken ground at a strong pace, brushing past startled workmen, smashing aside those who got in his way and leaving Bell to dodge the angry ones still standing.

Bell heard thunder, and the ground shook. Streetcars rumbled overhead, high above, on temporary timbers. Lights flickered. The water pipes swayed in their chains. On he ran, ignoring shaken fists and shouts of foremen, air storming through his lungs. The tunnel changed abruptly. Gone in an instant was the muddy floor; gone the men shoveling and picking. The floors, the walls, the ceiling, had turned to stone. The builders had hit Manhattan Schist in their drive north to Grand Central Station. The bedrock beneath the city had risen to the surface, and the tunnel was boring into it. The space felt more like a mine, with jagged walls and low ceiling and the whining rumble of steam drills.

Free of the mud, Isaac Bell poured on the speed. The man ahead of him was tiring, stumbling occasionally, and Bell was catching up. Better yet, Bell thought, the tunnel would soon come to an end. It looked like the only way out would be up one of the shafts where steel buckets were hoisting excavated rock by steam derrick. That his quarry had at least four guns and he had only knives did not slow him.

Suddenly, the man scrambled up the side of the tunnel, where it opened into an exposed gallery, and ducked under ropes that had been stretched to block off the area. Light spilled down from above. It looked like there was an opening to the street. A foreman came running from the other direction.

“Get out of there, you damned fool,” he shouted. “That chunk of work is loose.”

A shaft of daylight fell on the man Bell was chasing and Bell saw his face was still covered by the bloody bandage and the hat. But his eyes were gleaming as if in triumph, and Bell knew that he had seen something to his advantage. Bell ran harder. The man scrambled up the slanting side of the gallery where a section of bedrock had broken loose from the wall and slid down on the floor.

Bell could see that layers of the bedrock slanted at a steep angle. An immense chunk was propelled like a toboggan about to slide down an icy slope. He caught up with the foreman, who was shouting, “That’ll kill you! Get down from there, you idiot! Hey, what are you doing? Don’t do that. You’ll kill us all.”

The man had found a heavy pick and was using it to dig into the crumbling rock and pull himself higher up the slope.