Pure Chaos is the twenty-seventh episode and the first episode of the second season of Sonic X.
This is the beginning of the Sonic Adventure Arc of Sonic X.
As Knuckles the Echidna rests beside the Master Emerald thinking over the story of his life, he wakes up to find Chaos next to the shattered Master Emerald. Unaware that this is Eggman's doing, Knuckles assumes that Chaos is behind the shattering of the Emerald and goes on to attack it. However, the beast blindsides him and escapes, and suddenly Angel Island falls into the sea next to the Mystic Ruins.
Big is sleeping on his bed when something falling from the sky crashes. Froggy, his best friend, awakens and spots some strange blue liquid comes up and he swallows it. Big wakes up and asks if his pal is okay and sees that Froggy has somehow grown a tail. He is worried about Froggy, who is driven insane by the possession. Then Froggy swallows the Yellow Chaos Emerald (which Big calls his lucky charm) and hops away with Big in pursuit.
In Station Square, Sonic witnesses a stand-off between human police forces and Chaos, a water monster. Then it starts destroying everything in sight, scaring the people away. Chris, Amy, and Cream start running away while it's not looking. Elsewhere, Sonic catches sight of the commotion and steps in to help stop it. Chris is happy to see Sonic again. Sonic begins to fight the creature and easily defeats it, but it escapes through a drain before the hedgehog gets answers.
In Eggman's new fortress, he making a new line of robots: the E-100 Series, consisting of E-101 Beta, E-102 Gamma, E-103 Delta, E-104 Epsilon, and E-105 Zeta. Gamma's training involves him seeking and searing the Sonic doll in Final Egg. After that, Eggman pits Gamma and Beta to a small duel. Gamma achieves victory, but Beta's systems overload. Eggman then tells Decoe and Bocoe to have Beta to board the Egg Carrier for repairs and an upgrade. The flying fortress, the Egg Carrier, flies off into the skies.
The next day, Tails flies in the Tornado-1 when spots Wile E. Coyote, who goes ballistic and flies a biplane Red Baron-style in a vengeful attempt to shoot The Road Runner. Tails chases Coyote down until he makes his plane suddenly crash by the beach in Station Square. Sonic meets up with Tails again. He reveals that the Tornado-1 was powered by a Purple Chaos Emerald and the two plan to meet in the Workshop in the Mystic Ruins to plan the X Tornado.
Here, they are met by Eggman in the Egg Hornet. Sonic jumps onboard his Egg Hornet, but Eggman activates his Egg Hornet Drills and knocks Sonic off. Just as Eggman is about to drill a hole in Sonic's body, Tails throws a Power Ring in Sonic's hand, and Sonic destroys a drill and the Egg Hornet. Eggman steals Tails' Chaos Emerald and feeds it to the creature whom he calls Chaos. He explains that every time he gives Chaos one of the Chaos Emeralds, its power will be absorbed by Chaos.
After Chaos 1 beats Joey and Tristan with Chaos Strike (which confuses Tristan), Sonic and Tails counter Eggman's plans by getting whatever Chaos Emeralds they can for themselves. Once they arrive at Windy Valley, Sonic and Tails walk around and search, and Tails is almost blown away, but Sonic just caught him at the last second. Tails says that the Chaos Emerald is buried underground, so Sonic uses a Power Ring to dig underground, and finds the Blue Chaos Emerald. And with that Emerald, it will be easier to find the others.
Sonic and Tails then hop in the X-Tornado and find the next Chaos Emerald. Big finds himself in Station Square, where he finds the crazed Froggy go in the sewers. He hoists a black car (which fans find interesting), and follows Froggy to Twinkle Park. Big manages to fish Froggy out, but the crazed amphibian retreats. Knuckles arrives in Station Square to find the pieces of the Master Emerald. He finds a few pieces in Speed Highway. At Casinopolis, Sonic and Tails find the White Chaos Emerald. But Eggman arrives and takes the Chaos Emerald from Casinopolis. Knuckles sees that police are indentifying the crime that happened since there's a hole in the building. Knuckles asks what it is, and a policeman says it was a glowing object that fell from the sky, and Knuckles and the police go inside and look, and find a piece of the Master Emerald. Knuckles picks it up, but is transported to a version of Mystic Ruins 4000 years ago. Knuckles walks around and finds a echidna named Tikal with her father, Pachacamac. Tikal begs her father not to seize the Chaos Emeralds, but as her father ignores her, Knuckles is transported back to Casinopolis. The police decide to let Knuckles keep the piece of the Master Emerald, and Knuckles continues his search.
He then spots Eggman heading into an elevator in the hotel. He notices the shine in Eggman's hand and believes it to be a piece of the Master Emerald so he follows Eggman. An angry Knuckles shows up asking Eggman about the Master Emerald which also made its way into the Chaos Control. Eggman then gives Chaos 1 another Chaos Emerald transforming him into Chaos 2. Knuckles tries his hardest to fight Chaos 2, and with luck he manages to defeat it. Afterwards, Eggman sucks up Chaos 2 into his Egg Pod and tells Knuckles that Sonic is after the emerald pieces! This gets to Knuckles, wondering why the blue blur would want them. He then heads into the jungle (where a power-up is found). Knuckles heads to Red Mountain, finds 3 more shards. Team Lyoko are positive that Eggman will be back, as well as the Chaos creature.
- In the episodes based off of Sonic Adventure, the emerald colors are now match up with their game counterparts.
- Wile E. Coyote's new biplane Red Baron-style was better than the old biplane in Just Beep Plane.
- The Egg Carrier's physical design is the same as the Egg Carrier from Sonic Adventure.
- E-105 Zeta bears more resembelance to the E-1000's design.