Sonic plays a note on his guitar, and then impresses Tails by racing over to him and arriving before the note does. Tails notes that it's been a long time since he last heard a guitar, and Sally notes that it's primarily because of Robotnik's ban against music. Sonic begins to play the guitar for his teammates, only for the music to carry to Mobotropolis, where Robotnik hears it and yells. Snively Robotnik then enters, informing the doctor of a great discovery that he's made, only to be informed by Robotnik that he was screaming because of the musical note. Robotnik quickly determines that Sonic must be responsible, and Snively then explains that he may have the perfect means of paying them back: a device that can miniaturize living beings, though only for an hour. Robotnik is confident that he'll have plenty of time to catch the Freedom Fighters if they're stuck at that size, and turns to his Freedom Fighter Finder, which will enable him to determine when Sonic and the others emerge from the Great Forest.
Snively, meanwhile, has been humming the tune Sonic is playing, and Robotnik chases after him in outrage, intent on using the reducing device on him first. Some time later, Sonic leads his friends to the abandoned Mobius Concert Hall, which is where he found his guitar. He also reveals that there are plenty of instruments for everyone, and the group heads in to retrieve them before they can be spotted. To their sorrow, the hall is a run-down shadow of its former self, but Sonic attempts to distract them by leading them towards the orchestra pit. They are then struck by a ray from the reducing machine, and Robotnik swoops in on them with a mobile Roboticizer with a vacuum attachment, intent on sucking them up.
Robotnik sets his sights on Sonic, determined to capture him first, but Sonic is still in possession of his speed and manages to escape. He then uses it to cut his way into a cardboard box, releasing a wave of old concert programs that are sucked into the vacuum, clogging it. The miniature Freedom Fighters then hide from their antagonist, while Sonic deliberately antagonizes him, drawing him towards the orchestra pit. Robotnik's machine falls into it and is destroyed, only for Sonic to whip out a handheld model and suck Sonic up. Before he can Roboticize him, however, the Freedom Fighters use a cello to launch bows at Robotnik, knocking the device from his hand and driving him back. Then, to Robotnik's horror, the reducing effects wear off and the Freedom Fighters return to normal size, including Sonic, who breaks out of the vacuum.
The Freedom Fighters demand that Robotnik leave, but are then informed that he's sent for his Badniks, who will surround the hall. As he gleefully anticipates turning the Freedom Fighters into Robians and then having them destroy the concert hall, he is then horrified as the Freedom Fighters employ their secret weapon: the instruments. Robotnik flees in agony, and Rotor finds a perfect solution to the Badnik problem: the miniaturizing device. Not too much later, Robotnik's office is filled with miniature Badniks, which Robotnik orders Snively to remove before they return to normal size.