Sonic returns to his planet after releasing the seven chaos emeralds into space.  Sonic’s friends are watching the skies for a meteor shower but get a surprise when an Alien named Cosmo crashes her spaceship right before their eyes! As she is recovering, a Metarex lands on Earth, destroying everything in its path in search for the Planet Egg. Sonic, Knuckles, and Tails battle the Metarex, but can't stop him from escaping into space. As Cosmo introduces herself to Sonic, an old friend makes a suprise appearance.