Mercy and her sister Charity have never questioned their consistent daily routine They live at night, sleep during the day and see their widowed father only rarely - their house shrouded in perpetual winter But a chance meeting with the mysterious Claudius sets Mercy to questioning everything she has ever known - not least the truth behind her mother's death Bit by bit she traces her parents' story through the past, seeing herself as a young child, silent witness to the dramatic events Claudius himself plays an enormous part in - only when she has pieced together the truth can her world begin to move on