James Enys is committing a crime just by practising as a lawyer - a sixteenth century woman can't even appear as a witness in court. Unfortunately Enys is a woman, reluctantly pretending to be a man. She's starting to build her practice. Then she's summoned by Laurence Pickering, the King of London, who runs the City of London's large underworld. He wants her to find three extremely valuable jewels called the Three Sisters - balas rubies worth thousands of pounds which are also said to protect against the Plague. His nephew John Hughes has somehow managed to mislay them, perhaps because his wife has just died. Meanwhile Enys has to contend with the dreadful Puritan Maliverny Catlin's new friend the Reverend Pendry. He's an unlicensed preacher alluring Londoners with his oratory, prophesying the Apocalypse and inveighing against the wicked women of London. The pamphlets he's printing are scurrilous, obscene and in fact treasonous, which puts everyone concerned into danger, particularly Enys. Enys finds her path complicated by her friend the poet and the turned Jesuit, Felix Bellamy, while she tries to track down the rubies and steer clear of the Company of Watermen and their mysterious courtier.