Planet Secco’s Planet Egg has been returned, and as life for its inhabitants returns to normal Sonic and friends are honored for their heroism. Meanwhile, Knuckles has found one of the Chaos Emeralds, and Eggman is determined to take it.  He tricks Knuckles into believing he has changed his ways. Sonic and the others see through Eggman's trick, though. While Sonic and Knuckles fight it out, Eggman and Rouge both scheme to steal the Emerald. But a new Metarex gets in their way. It's a four-way free for all, with a Chaos Emerald as the prize!