She noted which cells had been remodeled and when, and by whom, and realized she did not entirely know; the older wing had been reworked before her time, and the plans, if they had ever existed, were not in any drawer she could find.

She looked at the infirmary, with its cabinets of small useful poisons and sleeping draughts, and at the sister who kept its only key, and felt the first cold touch of a suspicion she did not want to have.

She looked at the crypt, the oldest and least-visited part of the house, where the air was always cool and the sisters seldom went.

And everywhere she looked she found the same unsettling truth: a cloistered convent is built to keep danger out, with its barred windows and its bolted door, and is therefore almost entirely undefended against a danger that is already inside.