England, 1441: Lady Eleanor Cobham, Duchess of Gloucester, hopes to become Queen of England before her interest in astrology and her husband's ambition leads their enemies to accuse her of a plot against the king. Eleanor is found guilty of sorcery and witchcraft. Rather than have her executed, King Henry VI orders Eleanor to be imprisoned for life. More than a century after her death, carpenters restoring one of the towers of Beaumaris Castle discover a sealed box hidden under the wooden boards. Thinking they have found treasure, they break the ancient box open, disappointed to find it only contains a book, with hand-sewn pages of yellowed parchment. Written in a code no one could understand, the mysterious book changed hands many times for more than five centuries, between antiquarian book collectors, until it came to me. After years of frustrating failure to break the code, I discover it is based on a long forgotten medieval dialect and am at last able to decipher the secret diary of Eleanor Cobham.