She nodded. “Same sort of thing as the others. These motor areas of the brain were burned, actually burned! It’s as if some nice, normal cells just suddenly decided to stop producing the nice normal acids they need and suddenly devoted their time to producing sulfuric acid or something. How’s it possible, Mark? How’s it possible for just a few cells in a particularly critical spot, all in a group, to suddenly produce a destructive series of chemicals for a period, do their damage, then let the surviving ones return to normal? Even cancer, once it starts, keeps doing what it’s doing. This was triggered only in a few centers of the brain, critical centers, within a couple of hours in just about everybody in that town, then stopped. How is that possible, Mark?”

He shrugged wearily. “You tell me. You know LSD, though?” She nodded, wondering what he was getting at. “It’s a catalyst. Does just about nothing itself. You take it, it goes through the brain, trips a few wrong switches, then leaves, either in body waste or skin secretion. It’s almost out of the system by the time you get the full effects.”

She frowned. “You think we’re dealing with something like that here? A catalytic agent?”

He nodded. “It’s the oddballs that give it away. Remember in every case we had not only the town zapped, but also a number of people in other places who’d merely been in that town? Well, the magic number is three days, and maybe with a little more work we can pin it down to certain hours within those three days. At least we have a couple of people who were in Berwick in the early morning and left and didn’t come down with their disease, and we have a few more from Boland who were in town three days earlier, getting there late in the day, and didn’t get it, either. I bet we find those truck drivers who were in Cornwall were there within certain hours.”