"The Reverend Mother is delighted with her new entrant to the convent. Young Sister Gertrude is well-educated, has worked for an accountant and has an appealing sense of humour. But one autumn morning, Sister Gertrude is found dead inside a small wooden shed, just beside the river. Surely a young nun could not die from alcohol poisoning? But when the Reverend Mother delves more deeply into Sister Gertrude's background, she finds some puzzling anomalies....