“Who is this child? And why should we consider what he thinks? The explosion was the work of anarchists, rousing the workers to shut down the mill before the improvements could be made. Those responsible are probably gathered at the gate outside this very minute.” Earnshaw pointed to the eastern wall. “There have been rumblings for weeks that they planned some action. Mr. Coombe worried there would be trouble, and trouble there was.”

“No.”

“I beg your pardon.” Earnshaw turned to Rhynwick.

“I said no. Your assumptions about the explosion are incorrect.” The scientist passed by them without looking, and they followed in his wake.

“Why don’t you tell us what you’ve deduced, Rhyn?” Hoffman asked.

“The blast originated here. In this passage, traveling into both the warehouse, where it dissipated quickly by blowing the wagon doors open, and into the working floor of the mill, where it expended energy upward.”

“Preposterous,” Earnshaw said. “I was here when it happened, and the blast came from the milling room.”

Rhynwick’s eyes swiveled toward the accountant, but they did not linger. “It is quite obvious. Look at the blast patterns. They travel in both directions from this point.” He raised a slender, soot-covered finger, tracing the lines that radiated outward from the wall opposite Mr. Montgomery’s office door.

“That’s where two men were shoveling up a flour spill. They had toppled a load they were trundling to the warehouse.” Daniel toed a twisted bit of metal. “They were thrown against the wall here. This is all that is left of their cart.”

“Yes, yes, that explains it.” Rhynwick snapped his fingers. “Shoveling spilled flour.”

“What are you on about?” Earnshaw snapped. “Are you saying the two men who died in this hallway killed themselves? Were they bombers? Did their bomb go off prematurely?”

“What bomb? Where are your eyes, man? There was no bomb. At least not the type of which you are thinking. If this were a black powder explosion, there would be remnants of the kegs that held the powder. There would be at the very least a hole in the floor and in the ceiling as well.” Rhynwick pointed down and then up before poking once again through the mangled cart and twisted shovel blades.

“If there was no bomb, what caused the blast?” Daniel asked.

“Dust.”

Daniel looked at Ed and then the engineer. “Dust?”

“Yes. The conditions were perfect.” Striding down the hallway, then spinning on his heel and returning, the young man’s eyes measured the space. “Didn’t you know flour dust was more combustible than black powder?”

As a point of fact, Daniel hadn’t.

Rhynwick’s shoulders slumped at their blank expressions. He rubbed his forehead, leaving a black smudge behind. When he looked up, his face had fallen into patient lines.

“Flour is a starch. Which means it burns easily. Any starch, when in powder form, exposes far more surface area to the oxygen in the air than it does when piled or sacked or stored in a barrel.”