As she travels through Waltham Forest, Queen Elizabeth I is ambushed by masked gunmen who leave her carriage riddled with holes before disappearing into the night. Knowing that the perpetrators have the Queen's carriage route, her Private Secretary, Sir Francis Walsingham, must find the mystery assailants before they can strike again.

While Queen Elizabeth's Privy Council debates how to best secure the throne in the wake of the attack and Catholic Spain's further intrusion into the Low Countries, the queen herself searches for the ultimate weapon to protect her country and throne: Greek fire, the recipe of which disappeared with the collapse of the Byzantine Empire.

She orders her friend John Dee--scientist, philosopher, and spy--to rediscover this vital secret, despite his misgivings. For he understands that in a world fraught with coded messages, ruthless adversaries, and deadly plot, his mission to secure his nation's future may prove impossible, unless he deploys the most effective weapon of all: intelligence.