England, mid-1580s. Facing an array of international foes and torn internally by religious strife, England finds that its safety depends more than ever on a slight woman of exceptional intellectual brilliance, a master of realpolitik - Queen Elizabeth I, the Virgin Queen, Gloriana. Elizabeth is revered like a goddess, her stature a shrewd political tool designed to hold her people together. And it's about to be destroyed by a dark revelation from a hidden part of her past.

Narrated by a defrocked nun, a poignant victim of Henry VIII's dissolution of the monasteries, Unicorn's Blood is about a dangerous secret, the existence of a private diary kept by the Queen as a young princess. Should this stolen journal, embroidered with a unicorn that has a ruby for an eye, fall into the wrong hands, its intimate revelations would destroy the entire edifice of Tudor government.

On one side are the persecuted Catholic recusants, desperate to bring down their hated tormentor; on the other, Elizabeth's own ruthlessly ambitious spymasters, eager to hold the trump card against the Catholics - and against the Queen. The prize is the key to the real Elizabeth, written at a time when her own life stood in the balance.