The Syndicate Crime Organization is an organization lead by the mysterious Mr. X whose ultimate goal is to rule the city and cause mass anarchy. They do this through a number of means, including using their money to control the government and the police force, and using a large army of thugs to strike fear and terror into the hearts of the city's population.
The Syndicate was successful in taking control of the city. With their money and influence controlling the city's government, and the police force either bought out or too afraid to stick their necks out, it seemed the city was doomed to be under the control of the Syndicate. However, three police officers, Adam Hunter, Axel Stone, and Blaze Fielding took matters into their own hands and took to the streets as vigilantes. Fighting their way to the Syndicate Headquarters in the city, they defeated Mr. X and broke the Syndicate's hold on the city.
After their defeat, the Syndicate spent the next year rebuilding their forces and plotting their revenge. One year after their defeat, they struck back, kidnapping Adam and using him as bait to lure Axel and Blaze into a trap. With their thugs taking to the streets to reclaim the city as their own, Axel and Blaze fought back with the help of Axel's friend, Max "Thunder" Hatchett, and Adam's kid brother, Eddie "Skate" Hunter. The heroes managed to fight their way to the Syndicate's New Headquarters and defeated Mr. X once again.
Bare Knuckle 3
After their second defeat, Mr. X and his Syndicate went underground, using Robocy Corporation as a front for their activities. Hiring a scientist named Dr. Dahm, who was capable of creating exact robot duplicates of people, Mr. X launched a new plan to replace important figures around the city, such as the Chief of Police, with robot duplicates under his control. To keep the police distracted, he had his men set up bombs around the city.
However, a defecting scientist from Robocy, Dr. Gilbert Zan, leaked this plan to Blaze, who shared it with Axel and Adam. Axel and Skate, acting on Adam's behalf, quickly took to the streets to track down Mr. X and the syndicate. Along the way, they received word that the Chief of Police had been kidnapped by Axel, despite Axel's claim that he hadn't seen the chief in months. It turned out the kidnapper of the Police Chief was a robot duplicate of Axel, which convinced the heroes that Zan's warning was accurate.
The fought their way to the Syndicate's new hideout, and defeated Mr. X once again. However, this Mr. X was also a robot duplicate. The heroes continued the search, and found where the Syndicate was holding the police chief.
In the bad ending, the chief succumbs to poisoning, and the heroes have no choice but to race to City Hall to stop the duplicate, who is supported by Shiva. The heroes successfully defeat Shiva and expose the fraudulent Police Chief, but Shiva refuses to tell them where the real Mr. X is. Zan vows that he will find Mr. X and destroy him.
In the good ending, the chief is rescued before it's too late, and the heroes finally find Mr. X, or rather, Mr. X's brain controlling a powerful robot body. With the threat of bombs set to go off all over the city, the heroes have to defeat Robot Y before that happens.
In the second bad ending, they defeat Robot Y. Mr. X's brain attempts to blow up his base and take the heroes with him, but Adam manages to rescue them. However, it's too late to stop the bombs, which detonate, killing many people and wrecking many buildings. It would take a long time to repair the damage to the city, and even longer to regain the confidence of the citizens.
In the final good ending, Robot Y is defeated in time to prevent the detonation of the bombs. Mr. X's brain attempts to blow up his base and take the heroes with him, but Adam manages to rescue them. Dr. Dahm, who was taken alive, names all the officials who were replaced with robot duplicates, and the robot duplicates are destroyed and the real officials are returned. Mr. X and the Syndicate are finally destroyed once and for all, and peace returns to the city.
Streets of Rage 4
It is currently unknown what role, if any, the Syndicate will play in the upcoming Streets of Rage 4.