The true threat
You would think by looking at the cover of this book that it's just another fringe conspiracy book about the government or some other secret society covering up the truth about the face on Mars and other controversial items that have found there way into the pop culture of today.
Far from it! Graham Hancock has got to be one of the most level headed writers of our day. And it's a good thing! We need more like him if we're ever supposed to find our way through this mess of misinformation and speculation.
While it's true that Hancock, Bauval, and Grigsby do bring up the possibility of there being signs of some sort of intelligent design behind some curiosities on the surface of Mars, they delve into the nature of why Mars is what it is-a barren, possibly even dead planet that may have once held life.
Hancock does a very good job of explaining the geological evidence that Mars was bombarded by some very large space debris, perhaps as recent as 15,000-20,000 years ago. He goes onto explain that this debris, be it asteroids or comets, is more abundant in our solar system than you would believe, and that the history of Mars could well be our future if we do not take the time to invest in discovering, cataloging these objects, and researching ways to avert the danger that could be waiting for us in the near future.
I would definitely recommend this book to anyone who has even a remote interest in this subject. It will open your eyes to a subject that, while still important, makes global warming pale in comparison.