This is my first Sigma Force book and I didn't like it much. The premise of the story is that in the very distant past Native Americans buried some kind of nanotechnology-fueled doomsday devices around the Earth in an attempt to save mankind from their destructive power. In the present day a couple of anthropologists innocently unearth one of these devices setting off a chain reaction which could destroy the Earth.
Sigma Force (a group of government scientist/tough guys) sets out to contain the threat while The Guild (ancient society of bad guys) sets out to obtain the devices for their own benefit. The good guys and the bad guys rush from place to place as the threat spreads and there's a lot of kidnapping and shooting and killing.
The story is replete with conspiracies within conspiracies, Mormon beliefs about ancient Israeli tribes coming to the New World, pseudo-science, old maps made of nearly indestructible unknown metals, the Founding Fathers involvement, secret codes, and much much more. For me, the story just seemed to boil down to a bunch of people (whose identities tended to bleed together a bit) running from one place to another trying to outwit and kill each other amid a hodge-podge of hard-to-understand conspiracies. Just not my kind of story.