What was the first part of this magnificent theory? To start with, Sabon floated the thought—I can’t even credit it with the term “idea”—that the gray caps were the degenerate descendants of a local tribe similar to the Dogghe or the Nimblytod (without asking either tribe how they felt about being lumped in with the gray caps, and without consulting their extensive oral histories), but a tribe that had been colonized and then subjugated by several variations of fungus found in both above- and belowground Ambergris. She claimed that the mighty city that had existed before Manzikert I razed it had housed a Saphant-type civilization predating the gray caps. She even went so far as to suggest that the gray caps had been a servant class to this hypothetical other race. (I found it highly ironic, given the fate of my books at the hands of reviewers, that by postulating this “other race” and leaving that question as the book’s central mystery, she so captured readers’ imaginations that no one thought to cry out, “Where’s the proof?”)

Pestle said, “Tell Duncan that he doesn’t need to worry about the gray caps.”

“They say you don’t need to worry about the gray caps, Duncan.”

“Ah, but I know that they worry about us, and that worries me.”

Duncan did a rather unconvincing imitation of a shuffling gray cap. If I hadn’t seen him do it before, I wouldn’t have known what he was trying to do.

“Half-wit.”

“Unappreciative pedant. But what else did they say?”

“Also tell him,” Mortar added, without a hint of threat, “that he might want to go into another line of work.”

“Ho ho! Haven’t you said the same to me sometimes, Janice? So how can you complain?”

“Do you want to hear the rest or are you going to be difficult?”

“I’m sorry,” I said to M&P, remembering a valuable bit of advice from Sybel about how it’s never too late to correct your course so long as you’ve not yet run aground. (Because Sybel was, of course, an expert on sailing metaphors.) “I’m sorry, but I was joking. I’m not really Duncan’s sister. I just like to claim I am sometimes, you know, because it makes things more interesting. My apologies.”

I turned to the rest of the tourists, who had regrouped in front of me and had become a little too interested in my conversation with M&P.

“Now, as we continue, notice the telltale Trillian period details in the building across the square—in particular the fluted archways, the broad columns, the fine filigree. Also note—”

“I don’t believe you,” Mortar said, with the kind of earnest emphasis that can be interpreted as sternly polite or quietly angry, depending on your inclination.

Not for the first time, I remember thinking that perhaps it was time to change careers again.