In the dim glow of a Parisian attic, young Léon stared at the yellowed pages of a book his grandfather had left him. The cover read: "Dandelot – Solfeo de los Solfeos."

And the PDF? Still floating around the web. Most people use it to pass exams. But if you find the 1954 version, and you sing past page eleven… well, check your floorboards.

Then, on page twelve, something shifted.

Years later, his jazz band released an album titled "Dandelot’s Ghost." The liner notes read: “Learn your intervals. You never know what’s listening.”