I've practically read this series backwards, or at least, in no recognisable order. However, it has not detracted from the fact that the Sigma Force series is truly excellent.
Ever heard of m state gold? Me neither, but apparently it's possible to create a fine powder from gold, by doing stuff to it that makes every atom split from every other atom and sit on its own. This gold has incredible properties, and unfortunately, they can be used for incredibly deadly purposes. An intriguing thriller, based on real science, well explained and utterly gripping. The characters are great, from Commander Gray Pierce, through Seichan, Monk, Kat, Rachel, and a whole host of other characters. I think Pierce is probably my favourite, but Monk has to come a close second. The novel delivers an excellent mix of ancient (and more recent) history, fascinating recent scientific developments, and action.
A massacre in a church and the theft of the bones of the Magi who visited Jesus at his birth launches the novel, and the action doesn't let up til the end. Nor does the plot wear thin. Highly enjoyable, although you'll probably get more out of the series if you read it in order, simply because everyone doesn't always make it(!)
On a slight aside, James Rollins also writes fantasy novels under the name James Clemens. I've just managed to get hold of one for the first time. Shall let you know how that goes :).