Visiting a London bookshop in 1995 or 1996, British musician DJ Cylob noticed a pile of booklets near the entrance, with a note indicating that they were free. He asked an assistant about them, and she said that she knew nothing, only that a mysterious person was leaving them.

Each booklet consists of 20 pages of rectangular symbols. There are no letters or numbers, not even page numbers. Analysis shows that 24 different symbols make an appearance in the collection, which is consistent with encrypted English text, though some appear only at the beginning of the booklet and other very similar symbols only at the end.

The meaning of all this has never been discovered. One possibility is that the booklet is not a message at all but a game accessory. But then why does it contain no text? And why was someone silently offering it in a London bookshop?