Katherine watches as she rises now, her prayers at an end, and with a chopping gesture she instructs the sisters to rise too, to fall into their customary lines. After a pause she leads them across the nave to where Sister Joan stands at the north door. Katherine and Alice fall in beside one another and walk with downcast eyes, but as they pass Sister Joan, the older nun leans forward and pinches Katherine’s elbow to make her look up.

Joan’s eyes are like slits, and her tiny, pointed teeth are bared in a grin. She is laughing at something and pointing at Katherine. Katherine feels cold wash over her.

Of course the canon has been seen.

Almost blind with despair, Katherine follows the sisters through the cloister to the chapter house. Stark within, the room is dominated by a dais on which the Prioress sits like a queen, her head bowed in prayer. The stone floor is spread with rushes that sigh underfoot as they enter and take their places on the low bench and still without speaking each sister raises her hood to cover her face in prayer. When the Prioress has finished her own prayers she would ordinarily read to them from the Martyrology, but today she reads from the Rule of St Augustine, chapter four.

‘The fourth chapter of the Rule’, she announces, ‘deals with safeguarding chastity.’

Katherine feels something twist inside.

‘What should you do,’ the Prioress asks, ‘if you notice within your sister a wantonness of the eye? Would you admonish her so that the fault does not multiply, but stands corrected? Or would you treat it as an infirmarian might treat a wound?’

The Prioress looks around as if for an answer. There is none. She closes the book and steps away from the lectern.

‘Let me tell you this remarkable thing,’ she says, ‘for it is an example that might inspire you. During the time of Bishop Henry there was a convent of virgins at Watton in the province of York, to the north of here, and they took in an oblate, a girl of five. She passed her girlhood happily enough, in prayer and silent contemplation, but as she grew older, she began to show signs of girlish abandon.’

The Prioress pauses to let her words sink in.

Katherine’s eye is drawn to the tight-shut door.

‘Now one day,’ the Prioress carries on, ‘when some lay brothers were brought into the cloister to carry out some works, the eye of this girl fell upon one of their number, a handsome boy in the full bloom of youth.’

There is a stirring among the sisters, all of whom can imagine such a thing, though few have seen it for themselves. Alice at last seems to have understood what is being said, for she begins moaning and swaying again, as she had in the nave.