Gareth Brown

In New York City, bookseller Cassie Andrews is living an unassuming life when she is given a gift by a favourite customer. It's a book - an unusual book, full of strange writing and mysterious drawings. And at the very front there is a handwritten message to Cassie, telling her that this is the Book of Doors, and that any door is every door. What Cassie is about to discover is that the Book of Doors is a special book that bestows an extraordinary powers on whoever possesses it, and soon she and her best friend Izzy are exploring all that the Book of Doors can do, swept away from their quiet lives by the possibilities of travelling to anywhere they want.

The world of unknowable objects - magical items that most people have no idea possess powers - has been quiet for decades…

But three current 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.

Within hours of arriving in Hong Kong, Magda is facing death and danger, confronted by a professional killer who seems to know all about unknowable objects. Returning to London, Magda 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…