Apparently the characters in this book had a previous adventure in Brown's BLACK RAIN, but you don't need to have read that one to get thoroughly caught up in BLACK SUN!
This is one techno-thriller that actually uses real scientific theories to rock the boat of the possible future. You'll be up late reading to find out how they try to overcome these obstacles---mysterious Mayan artifacts, a mad billionaire who plays for keeps and has his own private army, the combined might of American secret service agencies, not to mention clandestine surgical operations on unwilling patients in secret laboratories, kidnapping from said laboratories, getting chased by hordes of man- and woman-eating sharks... A really good read!
From back cover: In the heart of the Amazon, NRI operative Danielle Laidlaw makes an incredible discovery: a translucent Mayan stone generating massive waves of energy while counting down toward the infamous apocalyptic date: December 21, 2012. And somewhere, there are three more just like it. What power will be unleashed if all four stones come together? Who created them--and who has more of them now? Using a cryptic Mayan map and a prophecy that points to the end of the world, Danielle and her team race toward answers. But one staggering question remains: Were these artifacts meant to save us--or to destroy us once and for all?