Frank and Joe Hardy are bound for the jungles of Borneo, and the journey may be one of the most desperate and dangerous of their lives. Following a cryptic map sent to them by their father, the boys head into the heart of darkness, where they make a terrifying discovery: Fenton Hardy is on the brink of death!

Someone has injected Fenton with a fatal dose of Anthrax-B, and the Hardys have only seven days to find the cure...or lose their father forever. The news gets worse when they learn who and what they are up against: Assassins. Experts in terror, the Assassins are the epitome of evil -- and international netwok that lives to kill!