While chasing the roaches, Oggy falls into a well that was hidden in his yard and he finds himself propelled into the belly of the earth along with Joey. The center of the earth is full of tunnels and passageways that all look the same and pretty soon, our two friends are totally lost. It’s getting hotter and hotter too and they have to escape from giant earthworms that also turn out to be very, very hungry…Official Synopsis, 
Journey to the Center of the Earth is the 29th episode of Season 4.
The episode starts with the roaches. They stole Oggy's nose and Oggy chases them. Dee Dee is playing it like a basketball and sends it to Marky then kicks it to Joey. Joey twisted Oggy's nose, making Oggy feel his catastrphic pain. Outside the house, Joey passes the bush being hidden and Oggy rushes it. Both of them was running through the bush. Joey jumps at the stone and Oggy is jumping the stone. It causes Oggy and Joey to fall underground. While falling down, Oggy has to kill Joey but he scrubbed his nose on the soil. Oggy felt his violent pain again. Finallly, Oggy swat Joey and retrives his nose back. Oggy balances himself at the stalagmites, but Joey jumped at Oggy, making Oggy fall down and he has holes in his body. Joey was squished by the stalagmite. He kicked the stalagmite and the stalactites fall down. Joey rushes and made it to the cave.
Back at the surface, the roaches Marky and Dee Dee go to Olivia. Olivia heard Marky and he told him that both Oggy and Joey fell down underground. Olivia never understand him because Marky used body language. Dee Dee was confused, and told Marky he can do better next time. Dee Dee wrote Olivia's notepad that the drawing was about Oggy and Joey fell down too deep. Olivia rushes to Oggy's house yard and Dee Dee spoke again. Olivia was in her excavation suit and saw a deep hole going down. Dee Dee told Olivia that if both of Marky and Dee Dee can have excavation hats. Olivia crushes a nut in half and puts the hat in their heads. Marky's antennas are too strong but Dee Dee's antennas are weak because he is fat. They gently go down where Oggy and Joey fell from a hole.
Back to the outer core of the Earth, Oggy and Joey saw odd stalactites and stalagmites. They go too far from a familiar cave. Some of them were difficult for normal people to walk. Oggy and Joey walked to a bridge where the deep river was made of liquid crystals. Joey was hungry so he ate a banana and threw the peel. Oggy accidentally stepped at the peel and slips himself. Oggy almost fell to the river, but Joey saw Oggy that he almost fell down, he ignored him. But he suddenly saved Oggy and flew high then back down the bridge. Joey gave Oggy's hand fur glove back to Oggy. Both of them heard their stomach growling and grumbling. They were hungry. Joey told Oggy to eat the mushrooms and Oggy accepts. They made hot mushrooms by frying it in a green fire. After swallowing the mushrooms, their stomach made some xylophone vocals and they laughed. The giant worm came and Oggy and Joey scream then run away from the worm. It was the end of the line. They fell to the river and slide down.
To the trio. Dee Dee licks the stalagmite and Marky goes with Olivia. Olivia saw footprints then walks away. The stalagmite was stuck on Dee Dee's tongue then walks too with Olivia and Marky.
Oggy and Joey again. Oggy twisted his cloth to drain the water from his cloth. Joey saw uneven shapes of crystals that act like mirror. Oggy and Joey saw it then they laugh, then to another one. After that, they saw an even shape of crystal that look like a mirror. Joey laughs but Oggy swat Joey that the reflection was ordinary.
To the trio. Olivia saw the banana peel. Olivia walks away and threw the peel. It fell on Marky and Dee Dee laugh. He was about to eat the peel but Dee Dee want some too. They drag the peel inaudibly and wrinkles the bridge. A small part of the bridge broke. It continues to break and the trio ran to the safe place. Marky and Dee Dee fell but they had wings and they fly. They crash on Olivia's head. Olivia reminds the roaches that not too use their wings too long if not on sight. The two roaches saw a lot of mushrooms and they began eating them. They eat as much as they could, but their stomach make xylophone vocals and they laugh even Olivia. When the worm arrived, Olivia made the background spin around and scream without moving her mouth. The roaches cover themselves in their hat, but the were still okay. Olivia plans something. She tied the roaches in a fishing rod while the worm keeps on moving. They go even deep until reaching the river of no line.
To Oggy and Joey, they reach the near center of the Earth. The soil was too smudgy and slippery. The two of them resurface but they failed. The two of them landed on a stone where it is surrounded by lava. They saw Olivia and the roaches. Oggy had to reach the rod, but they fail because the string was too short. Olivia uses the rest of her cloth and ties the string. Oggy reaches the string and was pulled back by the worm. Joey jumps on Oggy's nose and soon, he met his brothers. Oggy rides with Olivia. The worm knows the shortcut to the surface. They resurface and covers the hole. Oggy released the roaches off the string. Oggy told the worm to eat the roaches. The roaches and the worm run over the town and the episode ends.
- This is based on the book Journey to the Center of the Earth written by Jules Verne.
- ↑ Oggy and the Cockroaches - Journey to the Center of the Earth (S4E29) Full Episode in HD (published by OGGY on Nov 11, 2016, on YouTube. Accessed Oct 31, 2019.)