|This location exists primarily or exclusively within the Sonic Underground continuity.|
Information in this article may not be canonical to the storyline of the games or any other Sonic continuity.
The Worst Castle is perpetually shrouded by clouds and plagued by lightning storms. Its rooms are old, dusty, and infested with creatures, and it also contains several dungeons with a trapdoor in every room. The castle is run by Bellok and his owl Hooter, who are its only known permanent inhabitants.
The castle is home to a magical mirror which, when stepped through, warps the user into another dimension. At the end of the episode, the mirror is destroyed and Worst Castle is torn apart by enemy ships.
While collecting data in the sewers, Manic discovered the figure of Queen Aleena (actually Dingo in disguise) pass by and drop a note on the ground. He chased after what he thought was his mother, but failed to catch up. He picked up the note, which was an invitation from his non-existent cousin Albert for Sonia to inherit Worst Castle. It was really a scheme laid by Sleet to thwart the Underground.
Sonia was elated at the idea of owning her own castle and hoped to use it as a headquarters for the Sonic Underground, while Manic thought it would help them find out more about their mother. However, Sonic was indifferent, as the castle was a long distance away and there were presumably no chili dogs there, so Manic and Sonia set out for the castle while Sonic remained in Robotropolis. Sonic eventually changed his mind and visited the castle after a battle with Sleet and Dingo; he had also obtained a pair of anti-gravity sneakers.
Upon seeing Worst Castle for the first time, Sonia found it beautiful, but Manic began to get creeped out. They were greeted by an old vampire bat called Bellok, who was the castle's caretaker. Bellok led them inside and showed them their rooms, which were full of bats and rats, causing Manic to become afraid and want to go home. Sonia insisted the castle had "potential" and that they persevere with it. Just then, Sonia thought she saw Queen Aleena for a split second, but Manic was unable to find evidence of this and suggested that they retire for the night.
The Magical Mirror
In her room, Sonia was trying on a dress in her mirror when suddenly, she saw something in its reflection. Queen Aleena was on the other side! She then stepped into the mirror and entered a new dimension. After breaking out of a dungeon, Sonic and Manic arrived at Sonia's room, only to find she had gone missing. Sonic approached Bellok for answers, and he admitted that Sleet had forced him to use Worst Castle as a trap for the hedgehogs, or he would eat his beloved owl Hooter. Meanwhile, Manic realized that Sonia was inside the mirror!
Bellok told the hedgehogs that the mirror was a portal to another place and that, according to Queen Aleena, it was very difficult to navigate. Sonic entered the mirror and found Sonia wandering alone, lost. She was looking for her mother, but she had disappeared. The hedgehogs found that speeding around would not get them out; they had to walk slowly. They caught sight of Aleena leaving the mirror and Sonic ran after her, but was beaten backwards because he was going too fast.
Back in the castle, Aleena found Manic sleeping in a chair. While he was asleep, she touched his forehead and told him to escape the castle by entering the mirror. By the time Manic woke up and Sonic and Sonia were out of the mirror, Aleena had disappeared once again. Manic had felt Aleena's touch and believed his encounter with her to be a dream. At that point, Bellok announced that Sleet had arrived, and the hedgehogs used the castle's trapdoors to destroy most of the Swatbots. Unfortunately, Sleet had summoned all units, and Worst Castle was swarming with fighter jets.
The hedgehogs and Bellok were surrounded by enemies and on the brink of defeat, when Manic realized they had to go through the mirror to escape. Sonic and Sonia were astonished, the latter concerned that they could be stuck in there forever if the mirror was broken, but Manic said he was told by Aleena in his "dream". Without hesitation, the four heroes stepped into the alternate dimension just before a missile struck the mirror, shattering it. As this happened, the heroes were whisked away in a gold light and teleported outside Worst Castle, where they watched it being wrecked by planes. Manic felt as though his "dream" was real, but Bellok knew it really happened, as Queen Aleena was nearby.