"Here on the back cover," Foster said. "A scuffed area. Since this is khaff, it cannot be an actual scar. It must have been placed there."
I grabbed the book and looked. There was a faint mark across the back cover, as though the book had been scraped on something sharp. I remembered how much luck I had had with a knife. The mark had been put here, disguised as a casual nick in the finish. It had to mean something.
"How do you know what the material is?" I asked.
Foster looked surprised. "In the same way that I know the window is of glass," he said. "I simply know."
"Speaking of glass," I said. "Wait till I get my hands on a microscope. Then maybe we'll begin to get some answers."
[CHAPTER IV]
The two-hundred pound señorita with the wart on her upper lip put a pot of black Cuban coffee and a pitcher of salted milk down beside the two chipped cups, leered at me in a way that might have been appealing thirty years before, and waddled back to the kitchen. I poured a cup, gulped half of it, and shuddered. In the street outside the cafe a guitar cried Estrellita.
"Okay, Foster," I said. "Here's what I've got: The first half of the book is in pot-hooks—I can't read that. But this middle section: the part coded in regular letters—it's actually encrypted English. It's a sort of résumé of what happened." I picked up the sheets of paper on which I had transcribed my deciphering of the coded section of the book, using the key that had been micro-engraved in the fake scratch on the back cover.
I read: