Dr. Eggman has come back to challenge Sonic and crew again to defeat his new scheme. Sonic the Hedgehog, Miles "Tails" Prower, and Knuckles the Echidna gladly accept and race off to tackle the doc's latest plan. Meanwhile, Rouge the Bat swings in on one of Eggman's old fortresses and discovers Shadow the Hedgehog in a capsule. After an odd encounter, Rouge, Shadow, and E-123 Omega join up to find out what happened to Shadow and to get revenge on Eggman.
At a resort, Amy Rose looks at an ad that shows Sonic in it with a chao and a frog. After getting over boredom, Amy, Cream the Rabbit, and Big the Cat decide to find Sonic and get what they want back. Elsewhere, in a run down building, the Chaotix Detective Agency receive a package that contains a walkie-talkie. Tempting them, Vector the Crocodile, Charmy Bee, and Espio the Chameleon decide to work for this mysterious person, so they can earn some money.