Autumn, 1583. It's the year of the Great Conjunction: an astrological phenomenon believed to herald the death of one age and the dawn of another. England's tentative peace is under threat and prophecies foretell the death of Queen Elizabeth and, with her, the end of the Protestant religion.
When one of the queen's young maids of honour is found murdered inside the palace walls -- astrological symbols carved into her flesh and clutching a sinister witch's doll -- Elizabeth refuses to believe the killer could be someone within her own court.
In the meantime, Giordano Bruno, now secretly working for Elizabeth's spymaster Francis Walsingham at the French Embassy, is closely monitoring a Catholic conspiracy funded by King Philip of Spain and a cousin of Mary Stuart. But his position is growing increasingly tenuous; though the ambassador trusts him, his presence has been noted by Lord Henry Howard, a devout Catholic who publicly opposes anyone associated with magic or esoteric knowledge.
Bruno has cause to believe there's a connection between the murdered girl and the conspirators at the embassy. But when a second maid of honour is killed in the same way following their meeting, he realises that the killer is watching him too. Determined to prove his worth to Elizabeth, Bruno must play a dangerous game: can he allow the plot to progress far enough to hand the queen the proof of conspiracy she needs, without putting her, England or his own life in danger?