Come to me! I need you! These are the words that bring apprentice healer Lassair awake one morning in the spring of 1092, shaking and trembling, covered in sweat despite the chill night. It is not the first time she has had such a dream, and Lassair – who is growing more aware of the strange power within her – knows that something in the spirit world is trying to reach her. Something increasingly insistent and threatening.

Soon, Lassair is certain that one of her loved ones is in terrible danger – but who? Travelling from Cambridge, where she is studying under the tutelage of an extraordinary man, she returns to her backwater Fenland village – to hear the dreadful news that a nun at Chatteris Abbey has been murdered. The same nunnery where her beloved sister, Elfritha, lives. Could the urgent summons have come from her? Lassair immediately sets off, full of fear, but the danger she will have to face may be greater than she is ready for . . .