From the author of the internationally bestselling The Book of Doors,another fantasticalstand-alone novel in which a trio of seemingly everyday people are members of a secret society tasked with finding and protecting hidden magical objects–ordinary items with extraordinary properties. The world of unknowable objects–magical items that most people have no idea possess powers–has been quiet for decadesbut the three current members of a secret society have remained watchfulmeeting every six months in the basement of a bookshop in London. They are pledged to protect their archive of magical items hidden awaysafe from the outside world–and the world safe from them. But when Frank Simpsonthe longest-standing member of the Society of Unknowable Objectshears of a new artifact coming to light in Hong Konghe sends Magda Sparks–author by day and newest member–to investigate. Within hours of arriving in Hong KongMagda is facing death and dangerconfronted by a professional killer who seems to know all about unknowable objectsspecifically one that was stolen from him a decade before. Magda is forced to fleeusing an artifact that not even the rest of the Society knows about. Returning to LondonMagda learns hers is not the only secret being kept from the other two members. And that the most pernicious secret is about the nature of the Society’s mission. Her discoveries will lead her on a perilous journeyacross the Atlantic to the deep south of the United Statesnow in pursuit of not an unknowable objectbut an unknowable person: the professional killer she first faced in Hong Kong. In doing soMagda begins to understand that there are even more in the world who are chasing these magical itemsand that her own family’s legacy is tied up in keeping all these secrets under wraps. Magic has always been too powerful to reveal to the world. But Magda will learn there might be something even more powerful: The truth.