Maggie Gilbert and her children, Jack and Alice, live a pretty normal life. That is, until Maggie starts looking into her family tree. In doing so, she uncovers a dark mystery that endangers her children. She has to solve the a mystery in the past, if she is to save her family in the present.

Together with a fellow genealogist, Zelah, Maggie unearths more and more details about the drowning of a small girl and the unsolved disappearance of Maggie's ancestor. Strange forces are at work, and they seem to be leaking into the present.

This supernatural mystery is set in and around Cwmbran and Newport in South Wales, and draws on real historical details.