Bookbinder Lily Delaney must unravel a mystery involving a missing man, a long-ago secret society, a murder, and the supposedly mythical, heretical Liber Numerorum --The Book of Numbers--in this compelling sequel to the national bestseller, The Bookbinder's Secret . Read on if you dare! That is the epigraph in the hidden journal found by bookbinder Lilian "Lily" Delaney when her friend, mentor, and partner John Caxton disappears after a stranger comes knocking on the bindery door. In the sweltering Oxford summer of 1903, while searching in his study for clues, Lily finds a hidden journal full of coded messages, written by Mr Caxton forty years before. As Lily digs deeper, rumours surface of a secret society he belonged to in his university days and tales of a book that should not exist - the mythical, heretical, Liber Numerorum. The Book of Numbers. But Lily is not the only one looking for Mr Caxton and the threats start to pile up. She races across the country, to auction houses, Oxford colleges and into the ballrooms of high society. As she learns more of Mr Caxton's past, Lily begins to suspect her kindly mentor is anything but.

When a member of his old university society is killed before her eyes, Lily fears Mr Caxton will be next if she doesn't find him soon. But even if she does, will he still be the same man she knew?.