This mystery follows the lives of three siblings across four continents as they track clues linking recent influenza pandemics to bioterrorism. Antartica Ben O'Reilly and a multi-national group of scientists discover an unusual influenza virus in an Adélie penguin colony in Antarctica. Ben is bewitched by the exotic Filipino PhD student, Tina, as they work to unravel the genetic code responsible for the unusual properties of the virus. Australia Ben and Tina while conducting field research, during the equine influenza outbreak, discover evidence of mafia activity in the horse racing industry. San Francisco Caitlin O'Reilly, a wild child with a dark past, but now a top detective with the San Francisco Police Department, finds evidence of Russian mafia activity on the west coast and pursues a relentless quest to uncover the mafia plan. Anton van de Linde, the adopted brother of Ben and Caitlin, is a successful infectious diseases specialist living a hedonistic life style. His character is scarred by the death of his parents and he leads a dissatisfied and empty existence yearning for the happiness of his childhood in Carmel Valley. Through Caitlin and Ben he unwittingly becomes embroiled in the mystery surrounding the Antarctic Code. Moscow Vladimer Lazovsky provides the iron fist needed to control the disparate groups within the Russian mafia, and under his leadership they have continued to increase market share. He embarks on a new, highly profitable scientific phase of mafia growth when he learns of discoveries in Russian laboratories.