The Sigma Force is back in action. (see Map of Bones read last August). A deadly microbe has turned parts of the ocean into a toxic, flesh eating monster. What the hell is going on? Gray Pierce and the other fun folks of the Sigma Force team up with the evil Seichan to try to keep their nemesis, the Guild, from using this biological threat as a new form of bio-weapon. The action takes place with Grey and Seichan in one group and Lisa Cummings and Monk in the other, focused in the Indonesian Islands, where this threat to humanity has its origins. The formula for action/adventure these days seems to require some puzzle solving regarding ancient writings or artifacts, and a mystery that has been hidden through history. In this book, the mystery is what happened to Marco Polo during his return trip from China, that caused him to lose most of his expedition, a secret that is intimately linked to the bio-hazard of today? It entails having to figure out a secret code on an obelisk that has been stolen from the Vatican, and it goes from there. The organizations manage to effect whatever actions they need done with minimal dealings with the real world, but hey, this is pure entertainment. Why quibble? There is some payload here, the Marco Polo bit for one, angel writing for another, bioluminescence for a third, and an intimation that there are awful things lying much nearer than we might have supposed, that are not necessarily entirely dead. It was a fun, fast read, and would be a good book for summer reading. This is not book club fodder.