
Sonic Underground
The Hedgehogs find out that Sonia has inherited a castle. She basks in the idea of having a castle for headquarters.

The Hedgehogs find out that Sonia has inherited a castle. She basks in the idea of having a castle for headquarters.

Robotnik organizes a track meet to lure Sonic into a trap.

Sonic attempts a solo rescue to prevent prisoners from being roboti-sized and is hit by a Memory Scrambler that erases short-term memory.

The Freedom Fighters run into a Swashbuckler, named Ari, battling Swat-Bots. Sonic diverts them, allowing Ari to escape. After hearing that Robotnik is holding his band of Freedom Fighters hostage, Ari decides to help Sonic free them.

Sonic reluctantly takes Tails with him to the Big City to find some cotter pins for the Freedom Fighters catapults. While in the City, Sonic is nearly eaten alive by his old dog Muttski, now a roboti-sized guard dog in the Junk Heaps

Tails brings a new friend home to Knothole - a baby Terra-Pod who has strayed from the herd that is currently migrating. Sonic, Sally, and some of the other Freedom Fighters return the Baby-T to its mom and the rest of the herd.

Robotnik severely upsets the ecosystem above and below the surface, when he sends explosive, Robotnik snake probes drilling deep under ground in search of oil lakes.

Santa Claus has made an announcement - he is retiring and has picked the perfect successor - "Robotnikclaus"! Sonic and his sister resolve to persuade Santa to return and set Christmas straight. When the two track down the Santa who made the announcement, they discover he is just a phony robot and the real Santa Claus is being held prisoner.

When Tails gets trapped in the "Warp of Confusion" (an Escher-like world of another dimension) by Robotnik's cousin, Dr. Warpnik, Sonic comes to the rescue and traps Robotnik and his badniks in the warp.

Tails and other Mobius citizens are lured into Robotnik's robotic games of chance, and when they lose they're sent to slave labor camps. Sonic rescues Tails and the others by beating the house in games of chance at Robotnik's Casino.

When Scratch and Grounder use Robotnik's new Slo-Mo Ray Gun to capture Sonic, Tails rescues him by reversing the gun and turning it on a tribe of friendly Tree Sloth People who become a high speed commando strike force against Robotnik.

Sonic saves a damsel in distress, and falls in love with her, not knowing she's a robot built by Robotnik. But when she has a chance to trap him, she helps him escape, realizing she has fallen for him.

Sonic and Tails find an underground world of diamonds, but they are held captive there by a miserly Mole-Troll. When Robotnik comes to capture them, he accidently frees them from the Mole-Troll, who teams up with Sonic and Tails to defend his riches.

Sonic outsmarts Coconuts, then stumbles into a Convention of Bounty Hunter Robots where Robotnik puts a price on his head. After Sonic defeats all the Robot Bounty Hunters, Robotnik creates Scratch and Grounder to be his S.S.S.S.S. Squad.

Robotnik captures a flute-playing Ninja crane, taps his martial arts knowledge, and transfers it to Scratch and Grounder.

Santa Claus has made an announcement - he is retiring and has picked the perfect successor - "Robotnikclaus"! Sonic and his sister resolve to persuade Santa to return and set Christmas straight. When the two track down the Santa who made the announcement, they discover he is just a phony robot and the real Santa Claus is being held prisoner.

After Sonic is almost sucked inside the Void, he finds a huge Ring which Sally believes is an ancient relic but it turns out to be trick of the Sorcerer, Nagus. Sally and Bunnie are drawn inside the Void and when Sonic comes to rescue them.

During a mission to one of Robotnik's factories, Sally is taken prisoner by Robotnik and Snively, who construct a roboti-sized "Sally" clone, complete with Sally's personality, and mannerisms. The double tricks Sonic into rescuing "Sally".

Sonic and the Freedom Fighters journey to Robotnik's lab in hopes of deciphering his roboti-sizer system. While underground, Sonic spots his now roboti-sized Uncle Chuck aboard a Badlands bound mine-train and devises a plan for his rescue.

Santa Claus has made an announcement - he is retiring and has picked the perfect successor - "Robotnikclaus"! Sonic and his sister resolve to persuade Santa to return and set Christmas straight. When the two track down the Santa who made the announcement, they discover he is just a phony robot and the real Santa Claus is being held prisoner.