You'd have to be mad to steal from the feared International Patent Office. But that's what Elizabeth Barnabus is about to try. A one-time enemy from the circus has persuaded her to attempt a heist that will be the ultimate conjuring trick. Hidden in the vaults of the Patent Court in London lie secrets that could shake the very pillars of the Gas-Lit Empire. All that stands in Elizabeth's way are the agents of the Patent Office, a Duke's private army and the mysterious Custodian of Marvels.
Elizabeth Barnabus lives a double life - as herself and as her brother, the private detective. She is trying to solve the mystery of a disappearing aristocrat and a hoard of arcane machines. In her way stand the rogues, freaks and self-proclaimed alchemists of a travelling circus. But when she comes up against an agent of the all-powerful Patent Office, her life and the course of history will begin to change. And not necessarily for the better.
In the divided land of England, Elizabeth Barnabus has been living a double life - as both herself and as her brother, the private detective. Witnessing the hanging of Alice Carter, the false duchess, Elizabeth resolves to throw the Bullet Catcher's Handbook into the fire and forget her past. If only it were that easy! There is a new charitable organisation in town, run by some highly respectable women. But something doesn't feel right to Elizabeth.