Autor regards the newcomer with a raised brow. "Agreed," he says, jotting down a note in his journal, "but it takes a while to derive ammonium nitrate from fertilizer, and I wanted to see if the proportions were correct."

"If I really wanted to damage something or someone, I would have packed nails or broken glass in them," he says casually, pointing out the half-pound canister of black powder with a massive fuse.

"Do you have a great deal of experience with explosives?"