Queen Elizabeth of England has always been the Virgin Queen – but what if she is no such thing? What if she hasn't been a virgin since she was a teenager?
And what if King Philip of Spain could show evidence of that, and worse, to the misogynistic Puritans surrounding her at Court? The Book of the Unicorn could destroy Elizabeth personally and publicly - but where is it?
A man hanging weeping from the manacles in the Tower of London knows something, although he claims to have forgotten who he is.
An old nightsoil woman will sell the Book for gold to the highest bidder - but she has disappeared among the boozing kens and bawdy houses of London. Winter has frozen the Thames, the Frost Fair is in full swing and dirty secrets are erupting everywhere.
And while the Queen fights to keep alive her cousin, Mary Queen of Scots, her own Court is turning against her.
Simon Ames, now Anriques, realises he's in a deadly race to find the Book and must betray his friend to find it. If he fails, Elizabeth will be destroyed and England with her.
And he and his family will burn at the stake for being Jews.