When Sonic and The Freedom Fighters take out Robotnik's main computer, they're trapped by SwatBots in an underground tunnel, only to be rescued by a handsome teenager named Griff. Griff takes them deep beneath the Big City, where Sonic has to fight off some RatBots. They finally arrive in lower Mobius, where a group of Mobians have taken refuge from Robotnik and built a community, which is dependent on an energy cube for all its power. Unfortunately, the energy cube is losing its power, which Griff keeps a secret. Later at Knothole, where Griff learns of Sonic's power ring, he steals the power stone from Knothole's grotto and returns it to lower Mobius to replace their fading energy cube. Sonic tracks Griff back underground, saves his from a pack of RatBots and ends up giving Griff a piece of the power stone.