Our invisible books are so popular that we've been out of them for a week.

Saturday afternoon near closing time a visitor was wandering around in the graphic novels. I asked, "May I help you find something?"

She said, "I had a book on the history of Los Alamos, but I lost it. Do you have any books on Los Alamos?" I led her over to the atomic history section, which has garnered much praise from historians and scientists as one of the most extensive and complete collections on the topic in the country.

She stared at it moodily. "Is this all you have?" our visitor asked.

I told her, "No store can carry every single book that's ever been printed, but perhaps I can make a suggestion."

"Well, I had this book on the history of Los Alamos. Do you have any books on the history of Los Alamos."

I made a sweeping gesture. She was unimpressed. "Don't you have any books you don't have?"

I mulled that one over for a few seconds, and figured that trying to make sense of it would require some cold rags for the back of my neck. "Do you know the title or the author?"

"Well, it had the word history in the title, I think. And maybe the. Like The History of Los Alamos or something like that. You know the one?"

"I'm sorry, but I need more information than that."

She began to talk to me very slowly and loudly to make sure that I understood her. "I. WANT. A. BOOK. ABOUT. THE. HISTORY. OF. LOS. ALAMOS. AND. THE. HISTORY. OF. THE. SCIENTISTS! IT'S. A. BOOK. THAT. I. LOST. DO. YOU. KNOW. THE. ONE. I'M. TALKING. ABOUT?"

So I went back to the cash register and pulled up the inventory of books about Los Alamos with the word history in the title. Lots of books. I named the top five or so, but nothing rang a bell with her. "No," she said, "I think the book may have had the word Los Alamos in the title. Or maybe not. It was all about the history of Los Alamos and the history of the scientists, I know that for sure. Do you have any books on the history of the scientists?"

Another sweeping gesture at the biographies. "Do you remember the author?" I asked.

"No. But I think the book was about this big a-square," she said, holding out a copy of Standing by and Making Do so I could calibrate her request. "Do you have any books about this big a-square? About the history of Los Alamos? It had the history of the scientists, too, I'm pretty sure."

When in doubt, go to the cash register and check the inventory. "The closest I can come right now is Jon Hunner's Inventing Los Alamos. But we're out of stock right now."

"Oh, that's wonderful! Where is it?"

"Out of stock. I'd be pleased to order it for you."

"Is it about this big a-square?"

"Yes. It has a bluish-green cover."

"No, no, this book had a different color, I think. Or maybe not. Are you sure you don't have any books you don't have?"

No, this isn't the book I want. It's not this big a-square.