The old professor in the back whispered to her neighbor: “Bernold’s ghost. I thought she only visited once a century.”

Frustrated, he skipped to Diagram 39. It showed a cross-section of a human mouth, but the lips were wrong. They were too symmetrical, too… tense. At the bottom, a handwritten note in the scan read: “Pour trouver le fantôme, il faut souffler là où il n’y a pas de trou.” (To find the ghost, you must blow where there is no hole.)

At dawn, the PDF on his screen had changed. The title now read: Bernold_La_Technique_d_embouchure_40.pdf . Page 39 was gone. Replaced by a single line:

“Who are you?” he breathed.

He blew.

Then the ghost appeared.