Sonic and The Freedom Fighters journey to Robotnik's underground air base in a mission to reprogram the launch data on Robotnik's fleet of StealthBot aircraft. While attempting to reprogram the StealthBot computer system, Sally receives a computerized message she believes is from her father, indicating that he may be located somewhere within the Dark Swamp. Despite Sonic's warnings, Sally and Antoine set off on a dangerous mission to find Sally's father, during which they are detected by Robotnik's radar system and lured into an underground trap. Meanwhile, during a high speed chase with Robotnik's SwatBots, Cat is captured and held as Robotnik's prisoner. Sonic must turn on the juice, dodging missiles, outwitting slimy creatures, and eluding Robotnikset booby traps in order to rescue his friends and eliminate the threat of the StealthBot.