In the arms of the Oak in the whisper of the River Elizabeth I has died and with her passes an era. Science promises to shed light where magic and folklore have offered shadows. Mared walks out of step with the changing world. For her the old ways continue to have power and meaning. But her father minister, soldier, physician and Master of Cynvael shows little patience with witchcraft and superstition. His eldest daughter should be more like her sister Lizzie, a committed advocate of this new age of reason: biddable, dutiful and easily domesticated. But Mared begins to suspect there is more to her father than his sermons and his experiments. As she uncovers dark arts as well as dark secrets, Mared must join with Lizzie to find truth in the shadows and to act. Reworking the legend of Huw Llwyd, The Sisters of Cynvael blends myth and social commentary in a gripping feast of language and invention.