Chapter 9: The History of Thresholds, and What Was Surrendered at Each One

The classroom for History of Thresholds was not on the timetable's stated floor.

Callum found this out the way he found most things at Dunhollow — by following the discrepancy rather than the instruction. The timetable said east wing, second level, Room 7. Room 7 existed. He had walked past it on his second day. It had a door of pale ash wood and a brass handle worn smooth and a distinct, unremarkable quality that made it very easy to look at and very easy to forget. He went to it at five minutes before the hour, turned the handle, and found a broom cupboard of ordinary proportions containing no brooms.

He stood with his hand on the handle and revised his approach.