Threshold is one of those books that you just can't stop reading. By that I mean at least once a year for the last 10 years. David Palmers novel Emergence was excellent, however, its plot & story lead to a limited set of readers, Threshold I felt appealed to a larger number of readers, as it has elements of fantasy, science fiction & a little of the occult with its deliberatly mis-spelled references to witches, wards, familiars, etc. Unfortunatley, there are no sequels to this book, as I have heard (but not confirmed) that the author passed away before completing the 2nd & 3rd books. If it's true, the genre has lost a truly gifted author and I for one will keep on re-reading his material for years to come.