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The episode starts on the island with Topaz being chewed out by the people flying Eggman's old battleship. Tanaka goes off to comfort Topaz and the two stand on the beach. Tails tries to say that the X Tornado can make it to the core. Tanaka comes in showing off a box made of a rare metal as Dr. Cadbury opens the box an emerald is shown and Rouge looks at it.

Down below Bocoe and Decoe doubt what will happen when they hit the lava. However Eggman transforms the hovercraft into an ATV and goes through a tunnel. The X Tornado takes off into the volcano and they find the same tunnel as Eggman but it was blocked off. Sonic tries to dig through but the cave almost collapses. Rouge finds another tunnel and they start down it as they come across glowing moss. Knuckles gets full of himself and Sonic and Rouge start moving on. The three of them continue down the tunnels. They then come to an area where they have to climb a tunnel but Rouge slips and sends them all falling to the ground. They continue moving deeper into the volcano but Sonic gets scared as they come across the water. Knuckles drags Sonic on and Rouge dives in after them and Sonic lays on the over side gasping for air. They find a waterfall. They start climbing a vine rope up further showing the exit is blocked. Knuckles starts to dig through and a light is revealed. As they go in they find ancient ruins as Tails and Chris fly overhead showing off the buried ruins with artificial sunlight.

Rouge and Knuckles start arguing but Tails tells them to stop. Elsewhere Eggman is busy typing away on a computer as he orders Decoe and Bocoe to go find food. Tails sets a few devices and they start to monitor the pressure.

Decoe and Bocoe find a giant slug but they find a huge cherry and decide to go for that instead. As they grab it they find it's actually part of a huge butterfly. They see the two robots being chased and Chris decides to distract the bug. However Chris, Decoe and Bocoe end up falling into an underground tunnel landing by Eggman. Just then the ground starts shaking violently. Dr. Cadbury explains that they are going to be in danger if they stay down there. He tells everyone to leave right away. Sonic runs off to get Chris and Rouge flies off in another direction.

Eggman has captured Chris and they start to move on as Knuckles and Tails continue setting things up Rouge and Sonic continue to search until Rouge finds a huge collection of gems. Eggman shows that he will cause a chain reaction by detonating in their current spot. Chris says that Sonic will stop him but it won't happen because he is about to set it off. Chris tries to stop him but ends up falling on his face. As the ground continues to shake a giant robot emerges from the ground with Bokkun running wildly. Eggman spots the giant robot and they run with Rouge coming in and grabbing Chris. Eggman and the others run as the robot continues destroying.

Eggman flies off leaving Bocoe and Decoe behind as the inner volcano starts to erupt causing the ground to break apart. Eggman's robots explain that a bomb will blow up all the volcanoes and Chris runs off. Rouge tries to stop the robot but is no match for its strength. Chris gets the detonator and Decoe and Bocoe link up becoming a huge combat droid, or at least they think they did as they are broken apart. Tails comes in with the X Tornado as Sonic and Knuckles battle the robot now putting any kind of dent in it. Not even Sonic with a power ring can harm it. Sonic decides to use the detonator and as it explodes the robot is destroyed. However the volcano starts to erupt and they escape to boat. Dr. Cadbury ends it by giving a brief recap of the ancient civilization. Rouge shows off her jewel but Dr. Cadbury takes it saying she can come look at it any time. The group gets worried about not seeing Bocoe and Decoe anymore but the two robots show up on the ship and they say they will join the group now wanting to be part of Eggman anymore.