The biggest mystery connected with this book is why anyone thought it was worth publishing.
in the first place there really isn't much book here (what did you expect for £2.99?). The book is a mere 8.5 x 10.5 centimetres (just under 3.5 x 4.245 inches) - that's small enough to fit in the average-sized man's shirt pocket with room to spare. Moreover, the main text only takes up 117 pages, with generous margins, leaving room for around 120 words per page!
Of course that wouldn't be a problem if only the comntents of the book were well-research and accurate, but they aren't.
For example, as early as page 11 we get the usual piece of information that:
"... the gospels that were chosen for inclusion in the Bible by the Roman Emperor Constantine in the fourth century were only those that dealt with Jesus as a divine figure (any writings about Jesus as a man were discarded and suppressed) the Bible contains no references to the personal life of Jesus."
Wrong, wrong, wrong and wrong!
1. The gospels in the New Testament were already widely accepted as core documents in the Christian faith within a hundred years of Christ's death in approx 30 AD.
2. Constantine had NO PART in selecting which books would appear in what we now call the New Testament.
3. Far from rejecting documents that revealed Jesus' human characteristics, it is actually the "gnostic gospels" which describe him as being a spirit "appearing to be" a flesh and blood human being. It is the New Testament gospels which describe Jesus as a truly physical, human being who weeps (John 11:35), gets angry (Mark 3:5), felt hunger (Luke 4:2), etc.
4. Likewise we are told about various personal relationships Jesus was involved in, not just those he had with the 12 disciples (see the story of Lazarus in John 11, for example).
In reality, far from explaining "The Da Vinci Code", it all to often simply repeats the errors in Dan Brown's book and in the books his book was based on.
Despite the apparent promise in the title to reveal the "Key to the Da Vinci Code" all we actually get in the first 107 pages is yet another flick through some points in "The Da Vinci Code" which have already been covered in most of the previous books on the subject.
The geographical information about locations in Paris, and the corresponding errors in "The Da Vinci Code" are all described in "The Rough Guide to The Da Vinci Code" (2004), for example.
In the final analysis this book could have been written with no more knowledge of the subject than could be gotten from reading two or three previous books on the subject.
Not surprisingly, then, the only "key" this book has to offer is a simple tautology:
If ever anyone finds some evidence that proves that the claims made in "The Da Vinci Code" are true, that will prove that the claims made in "The Da Vinci Code" are true.