The passage turned sharply to the south, hugging the foundation stones of the central receiver tower. Here, the floor was laid with broad slabs of blue-gray slate salvaged from the old quarry works, set dry without lime mortar to allow groundwater to drain through the joints into the lower channels. The air was colder here, chilled by the underground draft that rushed upward toward the central steam cooler.
Len moved along the left wall, placing each boot with deliberate, painful care. His right ankle was swollen to the thickness of a fence post inside his leather boot, the stretched joint cords burning like hot wire whenever his heel took his weight. He couldn’t eliminate the sound of his passage entirely. Every third step, the iron heel plate of his boot clicked against the slate flags with a faint, hollow snap that shook through the foundation stones.
Fifteen yards behind him, the hunter kept an unvarying pace.
It wasn’t closing the distance in a furious sprint. It was pacing him, its boots clicking with matching rhythm. It tracked the scraping sound of his limp through the damp air. It was using Signal Recognition—the eighth milestone, stolen on Day Five during the depot raid—to filter out the nonstop roar of the release chimney pipes and isolate the sound profile of Len’s boots.
