Royce shook his head. “Even if that one is blocked, the pressure will vent here. Both have to be closed. It’s not the spouts or the portals. It’s something else—something we’ve overlooked—something that can seal all the exits at once to make the mountain boil over. There has to be another master switch, one that locks all the portals closed.”

“How are we going to find that? Do you see how many gears are in here? And it could be any one. We should have brought Magnus.”

“Sure, with him it would be easy to find—in a year or two. Look at this place!” Royce gestured at the breadth of the tower, where the sun’s light pierced through skylights, spraying the tangled riddle of a million stone gears. Some spun, some whirled, some barely moved, and everywhere were levers. Like arrows peppering a battlefield, stone arms protruded. Just as the gears came in various sizes, so did the levers—some tiny and others the size of tree trunks. “It’s a wonder they ever learned how to vent the core.”

“Exactly,” Hadrian said. “No one knows what most of this stuff does anymore. The Port Authority leaves it alone for fear they might destroy the world or something, right? So whatever Merrick did, it’s a sure bet the folks in charge here don’t know anything about it. It’s got to be a lever that hasn’t been moved in centuries, maybe even thousands of years. It might show signs of recent movement, right?”

“Maybe.”

“So we just need to find it.”

Royce stared at him.

“What?”

“We only have a few hours left, and you’re talking about finding a displaced grain of sand on a beach.”

“I know, and when you come up with something better, we’ll try it. Until then, let’s keep looking.”

Hours passed and still they found nothing. Adding to the dilemma was the interior of Drumindor itself, which was a maze of corridors, archways, and bridges. Often they could see where they wanted to go but could not determine how to get there. Luck remained on their side, however, as they saw precious few people. They spotted only a handful of workers and even fewer guards. All of them were easily avoided. The sunshine passing through the skylights shone with the brilliance of midday, then diminished as evening arrived, and they still had not achieved their goal.

Finally, they headed for the bottom of the tower.