Hovering above the dense yellow fog of Skako Minor, the city of Purkoll is home to a tower base controlled by Wat Tambor and the Separatists. But inside the Separatists are holding a dark secret, protecting the key to their survival and their sudden strategic advantages in the Clone Wars. Known as the algorithm, the Republic soon discovers how the battle droids have suddenly become adept at anticipating the clone troopers' every move.