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 doctor's latest plan. Meanwhile, Rouge the Bat swings in on one of Eggman's old fortresses and discovers Shadow the Hedgehog encapsuled. 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 Chocola and Froggy, Cheese's and Big's best friends respectively. 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, Espio the Chameleon and Charmy Bee decide to work for this mysterious person, so they can earn some money.