After the spaceship that carried the Knothole Freedom Fighters into outer space was de-energized by Doctor Robotnik and Snively Robotnik, Sonic the Hedgehog uses the only auxiliary power left in the vehicle to land on the nearest moon, which happens to be Muckury. However, the ship is trapped by the muck. The Robotniks pursue the Freedom Fighters and also get stuck, but their ship transformed into a giant robot without arms. Snively proceeds to kick their enemies' ship under his uncle's orders, but the Robotniks find that the Freedom Fighters escaped. Before the trailing Robotniks can destroy the Freedom Fighters, Sonic quickly sculpts a statue of his arch-nemesis using the layer of muck on the ground. The doctor falls in love with his own image, which collapses on top of the Robotniks. Using his speed to clear a path in the muck, Sonic leads the Freedom Fighters to Robotnik's ship, which they use to return to Mobius.
- Muckury is a parody of the planet Mercury.