Chapter 20: Flitwick's Private Suspicion Becomes Evidence

Holmes heard the knock at quarter past eleven.

He had been in the room that Flitwick had lent him — a narrow office two doors down from the Charms classroom, smelling of cedar shavings and old spellwork — for forty minutes, working through the grid coordinates with a fresh sheet of parchment and the stub of a pencil that was becoming uncomfortably short. He had not lit his pipe. He was saving the tobacco.

'Come,' he said, without looking up.