The society of unknowable objects

Three members of a secret society have remained watchful, meeting every six months in the basement of a bookshop in London. They are pledged to protect their archive of magical items hidden away. But when Frank Simpson, the longest-standing member of the Society of Unknowable Objects, hears of a new artefact coming to light in Hong Kong, he sends the Society's newest member, author Magda Sparks, to investigate.