Delaney's True Purpose

Hermione placed the copied note on the coffee table and looked up at Ron. "The formula in that book roughly matches the residue in Delaney's bowl. If Delaney's analysis is correct, then this formula is exactly the same as the record left by that fifteenth-century Scottish wizard craftsman."

"So what?" Ron leaned back against the sofa. "Maybe it's just the same formula being passed down."

"The formula itself isn't strange. What's strange is that it appeared beneath Hogwarts," Hermione said. "As far as I know, that manual had a very limited circulation. Its author was only active in northern Scotland, and his formulas were mainly recorded in private manuscripts. A few copies were made later, but they were all concentrated in that area. For this formula to appear beneath Hogwarts, either the builder had read that manual himself, or he had come into contact with northern Scotland's crafting traditions. Either possibility means that the structures beneath Hogwarts are more complicated than we usually believed."

Harry sat in an armchair, pulled his fingertips from his pocket, and glanced down. The tracking mark's signal remained steady, pointing toward the castle's southwestern corner, neither particularly near nor far away.

He said nothing. He merely read the note once more, then folded it and slipped it back into the envelope.

Delaney's third letter arrived later than expected. While Hermione was looking through books in the library, a gray owl landed on the windowsill with a thin envelope tied to its claw, slightly thicker than the previous two.

She opened it and found two sheets of paper inside.

One was Delaney's handwritten notes, adding details to his residue analysis. The other was a hand-drawn sketch: a top-down layout of the underground space, with fine lines marking the cracks, stone pillars, Stone Platform, and the relative