Sonic, Manic, & Sonia - Jaleel White
Dr. Ivo Robotnik - Gary Chalk
Sleet - Maurice LaMarche
Dingo - Peter Wilds
Cyrus & Knuckles - Ian James Corlett
Queen Aleena - Gail Webster

Doctor Robotnik informs the citizens of Mobius that he's marrying Queen Aleena this very day. The Sonic Underground can't believe this, and they must put a stop to it. But is it just a trap...?

Robtnik captures and robotocizes the Queen's personal bodyguard, Argus. The band manages to free his will, but the effect is only temporary. During this time Argus tells them where to find their mother...

It's the trio's birthday and they're on their way to find Mobodoon, a legendary "vanishing city" that only appears a few years. Sleet and Dingo are hot on their trail, and discovering this wealthy town, decide that it's time to collect taxes...

While in North Mobius, Sonia stays with her rich friend Mindy LaTour. Sonic and Manic are there too, but they're on the trail of some Robotnik spies. What does all this have to do with Mindy's mysterious father?

Sleet has come up with a plan to steal taxes from a Duke and still force him to pay the same amount to Robotnik. Meanwhile the Sonic Underground are in the town preparing to play in a ball of the same Duke, and come across a neighbourhood of pickpockets...

Sonic meets an old friend, Cyrus, who tells him his father is being kept as one of Robotnik's scientists. He does not tell him, however, that he's actually spying for Robotnik because of this. When he goes with the band to Sanctuary, a safe haven for all the Mobian children, he has to make the ultimate decision: sacrifice his father or reveal Sanctuary to Robotnik?

Still on the trail of Queen Aleena, the crew arrive at Port Mobius, which turns out to be a village of Robotnik-worshippers. The reason for this is that Robotnik is protecting them from the legendary sea monster Mobideep, who had been sinking many ships in the past. Sonic must now face his fear of water or risk losing his siblings' lives...

The Sonic Underground arrive in Mobia in search of the Queen's Journal. In the city Sonia loses her memory and meets Raphi, one of the town's resistance...

The hedgehogs come across Lake Valley, a beautiful resort. But how can it be beautiful when Robotnik's controlling the rest of Mobius? The band's about to find out...

Sonia has been invited to a debutante ball, arranged by none other than Robink's right hand man Bartleby! Sonic helps her in going there without being caught, but even more problems arise when Cyrus chooses her to fly the captives of the "Predator" to safety...

Robotnik has created a super-fast robot, and he's organised a race for the top athletes of Mobius and the robot. But it's all a trap to drive Sonic out into the open... can he resist the competition?

Sonia inherits a spooky castle, but all is not as it seems when they stay there overnight...

In order to make a lot of money, Robotnik sells artifacts to the nobility of Mobius. But these artifacts are actually from more recent history; they are bombs, and they're about to go off...

The band finds a village that has been destroyed by its Freedom Fighter occupants. Why has this happened? It seems to be something to do with the Flybots all over the desert, as Manic finds out when he's injected with a mind-control toxin...

Using the essence of a rare plant, Robotnik manages to make Sleet and Dingo fast-- maybe even faster than Sonic. The Sonic Underground manage to get hold of it, but can Sonia and Manic resist the temptation of taking the drug themselves and being as fast as Sonic?

The band visit the Floating Island in search of their mother. There they meet Knuckles the Echidna, the island's guardian, who has been told by Sleet and Dingo that the Sonic Underground is after the Chaos Emerald...

Queen Aleena sends her children over to Speedster Island, a place Bartleby is trying to turn into a holiday resort. Sleet and Dingo are pretending to help, but they just want to robotocise the islanders, who worship three stone heads that resemble Sonic, Sonia and Manic...

The hedgehogs are tiring of the war: every time they destroy a factory another two take its place. Feeling as if they're not making any difference, they seek The Oracle, who gives them a task: to go to the (Roman-style) dimension he created, and overthrow the current ruler (who bears an uncanny resemblance to Sleet) and restore peace -- all without their powers...