We open in the desert area of Mobius as Sonic gets immediately caught in the void, the dimensional portal that Robotnik has control of. The suction of the void is so powerful that even the power ring is barely enough to help him escape. He does find a strange object and goes to give it to Sally, thinking she would know what to do with it.
Meanwhile inside the void we're introuduced to Naugus, the wizard who helped Robotnik create the void, as we learned in Blast to the Past. Even though he's been trapped in another dimension, he can still see the goings on outside of the void, and has a particular interest in the speed of Sonic and the mind of Sally.
Sonic returns to Knothole to tell her of the void, and the ring he found. It was from a legendary race of giants apparently. But nevermind that right now as Uncle Chuck sends info about Robotnik planning something big. Sonic goes off while Sally accidentally activates the ring, which takes control of both her and Bunnie, sending them off somewhere. Uncle Chuck warns Sonic of something called the "doomsday project". He knows very little, but will keep the freedom fighters informed.
Meanwhile, Snively discovers the opened void and warns Robotnik. We go to a flashback of Naugus testing the void and threatening Robotnik by changing his head to that of a crow. I guess King Acorn isn't the only one stupid enough to believe that Robotnik wouldn't double cross them. Naugus enters the void, and Robotnik immediately locks him in. Rule #1. Never trust anyone, especially Robotnik. However, this new situation and Naugus' possible means of escape has Robotnik particularly on edge.
Sonic returns to find Sally and Bunnie missing. He finds Nicole, and realizes something's up. Meanwhile, Sally and Bunnie get caught into the void. Sonic has a hard time getting Nicole to mention where Sally's location. He shakes the computer, which is enough for her to finally show what happened, finally realizing that, they went into the void. Inside the Void, Naugus uses mind control to try to get an answer about Sonic's location. He introduces himself to the two and Robotnik's double cross. He needs Sonic in particular to help him get out.
Sonic and Nicole try to find the void while Robotnik's fleet is on the way. Robotnk fears Sonic's involvement might mean he's working with Naugus and goes on the full assault. Sonic digs underground to escape while the void activates again. Sonic seems trapped, but then realizes that, oh right, he needed to get inside the void after all. Robotnik tries to seal the void, but there's heavy resistance, keeping it from being sealed.
Naugus introduces himself to Sonic and tells him of his desire to exit the void. Sonic and hte others try to escape, but Naugus traps them inside. They find a crystal palace that reminds them of King Acorn's palace.
And it turns out that the king is still there as well. He wants Sonic to help him escape the void. He appears weakened from the years of the void. Despite this feeling like an obvious trap, and not even second guessing, Sonic takes the king out of the void. But before Sally and Bunnie can realize it themselves, Ari arrives to tell them that this was indeed a trap by Naugus. Ari is with the real King and he has a tearful reunion with his daughter while Sonic arrives with Naugus. He let's Sonic go and mentions his intentions to get revenge on Robotnik.
While Naugus turns Robotnik's heads into several animals, he begins to crystalize. He allows Robotnik to escape, while Sonic releases the others from the void. It turns out that the king and Naugus have been in the void too long and are unable to stay in this dimension. Before they say goodbye, King Acorn gives Sally a list of the remaining freedom fighter groups. She promises to get him out eventually as the freedom fighters and Ari watch Naugus and King Acorn reenter the void. We end the episode with a sad Sally being cheered up by Sonic by telling her of their victory. But she becomes more worried about the bad influence on Nicole.
The Void is another strong episode of season two. We continue the heavy info dump that we've been given so far, giving us the history of Robotnik's betrayal on Naugus. Speaking of Naugus, he's definitely an interesting character, clearly evil, but more focused on getting his revenge on Robotnik first. He gets some of it, but not as much as he'd want seeing as the affects of exiting the void begin to affect him. It's good to see King Acorn again, as it's a great use of Tim Curry, and seeing Ari make his escape is also a nice touch, giving us a bit of a resolution to the events of Game Guy. Hey, if Ari can be saved, maybe they'll finally save Cat.
Maybe.
The episode's pacing was solid, had some great action, some great emotion, and even some great humor with Sonic trying to get answers from Nicole. It's also interesting to see Robotnik feel more vulnerable at the possibility of Naugus getting his revenge. Also, we get our first mention of the doomsday project, which will play into the end of this season. All this makes the Void one of the show's most important episodes and a must watch. Next time, it's back to Antoine with two more comedic episodes, and smooth sailing with the final four episodes.