In the last years of the Viking Era, as the traditions and old wisdoms are being replaced by the Roman Church, Astrid, a skaldm r who is learning to write royal sagas, takes on the task of recording the True Things so that they are not forgotten. When she realises that she must protect her baby from the King and the Bishop, Astrid runs away to the Orkney Islands to hide her daughter and the book.
Mercy is taken from a Victorian orphanage in Glasgow by a dangerous man. She escapes and meets Ann Radcliffe, a successful yet reclusive author of Gothic horror novels. Mercy joins Ann's household and is taught the art of storytelling. But she longs to discover her true identity, the answers to which may be found in a book her mother left for her at the orphanage.
Mia, who lives in the Blue Mountains, is given the ancient book Systir Saga at the funeral of her cousin. With the help of a university research assistant, she manages to decipher the early rune symbols and discovers that it points to an even more mysterious book buried somewhere in the Orkney Islands. Mia travels to an ancient rock mound on a windswept island to discover the true secret of the Systir Saga.