As long as anyone could remember, the Chaotix team has been the guardians of the secret chaos rings, of Angel Island. History has shown that the job as guardians has been anything than easy althrough the years...
In the summer of 3235, Angel Island and the chaos rings were under the greatest threat ever, as the island was attacked by the evil scientist, Dr. Eggman. Things looked dreadful for some time, as the island got invaded by robots and as the chaos rings were stolen. But after many fierce battles, the Chaotix team, featuring Knuckles the Echidna, Espio the Chameleon, Vector the Crocodile, Charmy Bee and Mighty the Armadillo, combined their powers, and destroyed Eggman's army and retrieved the rings of chaos.
The battle was over, and peace was restored. Although the efforts of the Chaotix were greatly appreciated by the inhabitants of the island, the Chaotix team went very unrewarded - not a single penny was paid out for the heroes work.
So what would the Chaotix team do now? What would a crocodile with an appetite for life, babes (and most important - FOOD!!), a bee which eventually would get tired of nectar, a hungry chameleon with a long taste-feeling tongue, and a starving armadillo do now?
Vector, Espio and Charmy decided to open up a secret detective agency. They would work for anyone with a good purpose, and with plenty of cash. However, Knuckles the Echidna left the Chaotix party shortly after the defeat of Dr. Eggman to remain as Guardian of the Master Emerald. Mighty the Armadillo was not too keen on the idea of starting a detective agency, and left the team as well. Without telling the Chaotix team exactly what he would do next, he left Angel Island and went down to the planet Mobius, the planet that Angel Island was floating above. The only thing he said before he left was that he had "someone to take care of".
Things looked gloomy for the detective agency at first. Weeks passed without any commission whatsoever. Until one day, when the remaining members of the Chaotix team eventually got a mission by a mysterious stranger: To save him from an evil force, and to destroy Eggman's new army.
Eventually, it turned out that Eggman was the mysterious stranger, and that he had been victim of one of his own projects that had backfired - the Metallix overlord, a giant robot in the shape of Sonic the Hedgehog, had taken over. After another dangerous battle, the Chaotix triumphed over the Metallix project in co-operation with several other friends (Sonic the Hedgehog, Tails the Fox, Knuckles the Echidna and several others). The only problem remaining was that Eggman in fact had no money to pay, and the Chaotix team were more or less back on square one - no money and their stomachs even emptier than before!
But the Chaotix did not give up that easily. They decided to give the detective agency another shot, and got new missions from time to time, enough to have enough money to survive on.
But one morning, a year later...
...things were not as usual...
Espio the Chameleon found himself waking in an unfamiliar house. "Where am I? What happened to me?" he asked himself. He then noticed that he had been injured and that several parts of his body had been covered with bandages.
After a lot of effort, he managed to climb out of the bed. Little did he know that his greatest adventure ever was just about to begin...
The story focus on the return of Emperor Metallix (better known as Metal Sonic) and his goal to once again rule the world. Espio and the other Chaotix members well as the Chaos Rings before Emperor Metallix and his forces do. As they journry around the world, they'll come across many faces (as the game features both old characters from the comics and games as well as a few fanmade characters) such as Fang and Rouge.