|Season 1, Episode 25|
|Air date||21 September, 2003|
Infiltrate! Area 99
Sonic and friends search everywhere for the last missing Chaos Emerald. Chris is a little bit depressed despite that he wants his friends to be able to go home to their world, but at the same time, he will miss them deeply. During school, Mr. Stewart notices this and convinces Chris that letting them return to their home is the best option. Dr. Eggman in the mean time has deployed E-77 Lucky to go out and find the seventh Chaos Emerald as well despite being very clumsy to fall off after taking its first step out of the Egg Fort II to which Decoe and Bocoe are heavily skeptical about.
Knuckles walks through Forrest Hill, worried about the Master Emerald and desperate to return home by all means. He concludes that it is up to him to reconcile the differences between Sonic and Eggman in order to get all the emeralds together and return home. Knuckles finds the Egg Fort II hiding in Forrest Hill and he also finds Lucky who follows him to Chris' house in order to talk to Sonic. After Chris accepts to pass his message to Sonic and his friends, he and Knuckles although it took them a while to realise that Lucky is no longer following them travel back to the Egg Fort II and make a deal with Eggman to combine collections of emeralds with the doctor in possession of them.
Chris takes the four Chaos Emeralds that Sonic and his friends collected without telling them and he and Knuckles take them to Eggman. Meanwhile Lucky has fallen in a dumpster and ends up wandering the South West Dump where he finds a box containing the seventh Chaos Emerald. Lucky contacts Eggman on the phone and informs him of the good news. When Eggman hears that Lucky has the seventh emerald he betrays Knuckles by activating a trap door underneath him. Eggman then reveals to Chris that he does not care about staying there or going home, he just wants to establish his Eggman Empire. Either world would not make a difference to where he would establish.
Sonic arrives in Forrest Hill in time to find Knuckles on the ground and the Egg Fort II taking off. Knuckles tells Sonic that Chris is kidnapped on board as well as the remaining six Chaos Emeralds, so Sonic chases after the ship.