"Big Trouble in Little Station Square, Part One": S.O.N.I.C.X. – the secret Sonic-hating organization – is at it again! They have a special serum that will turn Sonic into the monster they think he "really is." The problem now is: how do you catch the fastest thing alive?! It's a high-speed chase through the city with a special guest appearance by the Chaotix and an ending so big you won't believe it!
The Organizer is losing his patience with S.O.N.I.C.X. for their constant failures in attempt to stop Sonic. However, Doctor Kai Narasu plans to use highly viral mutagen, of which there is enough for 6 shots, to transform Sonic into the monster the organization sees him as. Hector Dragg and Dr. Narasu arrive on the scene, where Sonic is fighting Doctor Eggman and his robot squid. After 4 shots of the mutagen, Sonic remains untouched, and once he has defeated Doctor Eggman, he runs away, only to be chased by Hector and Dr. Narasu on a motorbike. Sonic manages to dodge another shot of mutagen.
Sonic then runs in the opposite direction, away from S.O.N.I.C.X., and Hector and Dr. Narasu follow Sonic to the Chaotix headquarters, where Sonic wants them to investigate what they are up to. Dr. Narasu aims for Sonic, but Charmy dives in front, knocking him away with his helmet, and Espio dodges it. Sonic leaves the headquarters to find Hector and Dr. Narasu. Unfortunately, Vector is shot by the mutagen and grows to a very large size, breaking through the Chaotix headquarters, before going on a rampage through the city.