From a book review on Amazon...
 
With THIS PRESENT DARKNESS, Frank Peretti broke onto the scene by graphically tearing back the veil between our world and the spirit world. Descending upon the small town of Ashton, angels, demons, and strongmen engage in vivid spiritual battle and we, the reader, are able to see it all unfold. Ever wonder what exactly a guardian angel might do? Here's one possible scenario.
While Peretti's theology on the subject may not be perfect (many of his ideas are pure speculation, but that's why it's "fiction"), he does most definitely give us a bold reason as to why prayer is so vital. Why prayer does, in fact, move mountains and can turn the tide in unseen spiritual battles that are taking place around us (as happens in the book of Daniel). For that reason alone, THIS PRESENT DARKNESS is worth reading.
 
This book was suggested by Amazon.  I assume it was brought to my attention because I was looking up another book.  I usually use Amazon to find out about a book if I think I may want to read it.  This was interesting because the reviewer states many of the writer's ideas are speculation, then in the very same sentence suggests this is a bold reason for prayer being vital.  Looks to me like a new twist on the whole faith theme that theists use to support their argument for the whole superior being idea.