The world of unknowable objects - those seemingly ordinary items that most people have no idea possess magical powers - has been quiet for years...
Indeed, there is a secret society whose sole purpose is to gather these artefacts together, and keep them safe from the outside world - and the outside world safe from them. The society meets every six months in the basement of a London bookshop, and it's at one of these meetings that Frank Simpson, the society's longest-standing member, reveals that a previously unknown item has surfaced in Hong Kong. He asks the newest member, author Magda Sparks, to investigate.
Within hours of her arrival in East Asia, Magda is confronted by a killer who seems to know all about these unknowable objects. She manages to escape, but only by using her own magical artefact that the society knows nothing about.
Safely back in London, Magda learns that hers is not the only secret that's been kept from the other members. And that the most pernicious secret of all seems to concern the very nature of the society itself.
The enormity of what Magda discovers takes her on a perilous journey - across the Atlantic to the deep south of the United States - in pursuit of an unknowable object and a seemingly unknowable individual, and answers about her legacy and the society she serves.
Magic may be too powerful to be allowed out into the world, but there is something even more potent: the Truth...