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.