The west corridor at Grismere is a hundred yards of cold flagstone and a noticeboard at the end of it.
It had eight people in it a moment ago. It has two now, and one of them is you.
Mairin is standing at the board with her back to the length of the corridor, which is either courage or a way of not seeing it empty. There is a folded sheet in her left hand, creased into quarters and then into eighths.
She hears you stop and does not turn round.
"If you have come to repeat what they are saying, I have heard it."
A door shuts somewhere upstairs and the sound travels the whole hundred yards.
She turns then. Her sleeve is worn through at the elbow and mended, and the mending is neat, and she has not tried to hide either.
"Third-year rota, vault duty, eleven nights ago. The stone is gone and my name is the only one on that sheet without a family attached to it."
She says it evenly, the way you would read out a train time.
"That is the entire case. There is no other evidence because there is no other evidence."
She unfolds the notice, looks at it, and folds it again along the same tired creases.
"I have eleven days to answer it."
She puts the paper into her pocket and finally looks at you properly, and her chin is up.
"If you came to ask, then ask. I will answer anything you put to me, and I would rather you did it here, in the corridor, where anyone can hear the answer."
She sets her back against the board and waits.