Childhoods of Al Capone, the future ambitious gangster who'll try to become the crime boss of the prohibition era Chicago, and Eliot Ness, the future head of "The Untouchables", a team of incorruptible agents formed to stop Capone.
Capone and his allies start running the show and earning top dollar from booze smuggling. Ness becomes the head of the newly-formed Untouchables and he and his law-enforcement agents start working on Capone's downfall.
Ness' team hits Capone's operations hard. One of the raids ends in a shootout and two civilians are killed in crossfire. This leaves Eliot worried that things might escalate out of control if the raids continue to be violent.
Ness uses a sleazy journalist to feed Capone with false information about his team's actions.
Lingle, the sleazy journalist Ness used to feed Capone with false information about Ness' operations, is found dead. Ness is adamant to find the perpetrators. What he uncovers is a web of corruption.
The head of a local worker's union that's on strike is approached by Capone, who offers him help in the battle for his union members' rights. Ness warns the man that offers from scheming Capone always come at a heavy price.
The hunt for a serial killer who preys on children becomes Ness' priority for the time being. Ironically, Capone is also after him for his own reasons.
In an effort to catch the child-killer as soon as possible, Ness agrees to a temporary alliance with Capone. However, Capone has no intentions of giving the killer up to the police. If he catches him first, he will kill him.
Ness agrees to send one of his agents undercover to infiltrate the Capone organization. He realizes too late how dangerous the mission actually is.
Capone's unwilling Chinese mistress, whom he bought for himself from her father, witnesses Capone committing a murder. Now all Chicago is after her and Ness must find her first.
Capone orders Frank Nitti to sponsor a nice low-tier Irish boxer and family man Tommy Dolan. Dolan starts winning fight after fight, not realizing they're all fixed. The public loves him but Capone plans to cash in on him.
Ness helps one of his men, agent Tony Pagano, find his missing sister, who's been kidnapped by the Capone organization and forced into prostitution.
One of Ness' men, agent Michael Malone, is found drunk with a gun used to kill a mobster. Ness doesn't believe that Malone is guilty of this murder, but Capone wants him dead anyway.
When Capone tries to expand and take over the numbers racket (a form of illegal lottery) in Chicago's South Side, Ness has no choice but to make a temporary alliance with the current numbers kingpin there in order to stop Capone.
Poor newsboy witness a mob hit, so Capone offers him money and a place in his crew to keep him quiet. He accepts, but things don't go so well for him.
Capone breaks off with an unstable actress. Hurt and jaded, she begins to stalk him and his family.
There's a new player in town - the moonshiners. When they cut into Capone's profits, he has no intention of tolerating competition, but they won't back down either. Instead, they propose a one-on-one showdown at sunrise.
Ness finds out that Capone is trying to form an alliance with the heads of the New York mafia, Lucky Luciano and Meyer Lansky. He must do whatever it takes to stop this and some bad publicity in the press might help.
With Capone dealt with for the time being, Ness has a new target - the Chicago's corrupt mayor with mob connections.
Nitti continues Capone's bootlegging operation. Meanwhile, Ness and Capone agree to a box match against each other.
Capone's wife and daughter become the targets of a deadly assassin. Capone's crew helps him find a way out of jail.
Ness sees a chance in Capone's release to influence Nitti and take down the corrupt mayor.
Ness must try to stop Capone from making a deal with the corrupt Cuban President and his government that would expand Capone's business and influence.
Having no allies within the corrupt Cuban regime, Ness and his team get in touch with the Cuban rebels who are trying to overthrow the president and his government. If they succeed, Capone's plan to smuggle liquor from Cuba is D.O.A.
The new Chicago mayor Anton Cermak clamps down on the mob. When even Capone's wife is put under arrest, Capone puts a hit out on him.
Chicago is put under martial law and a tough army general is sent to clean up the streets and destroy the mob. Ness doesn't like him or trust him and opposes his methods openly.
Capone plans to take over the New York mob. Ness has to stop him, but a power-hungry prosecutor stands in his way.
Ness is told that he's been in coma for a year. His family is gone, but his archenemy, Capone, is behind bars for good. Ness suspects something doesn't fit when he's asked about the whereabouts of one of his informers.
Agent Robbins, one of Ness' men, falls for a local Russian girl, not knowing that her father is in Capone's debt.
When Capone's hitman is found not guilty for killing a cop, the policeman's son vows revenge.
A radio singer is targeted after she witnesses Capone's bloody attempt to take over a radio station.
One of Ness' men, agent Malone, believes he knows who's behind the killings of German immigrants in Chicago. A German WWI spy and Malone's archenemy from the war is back in town.
Agent Malone has had enough of perpetual crime-fighting and just wants to settle down with his better half. However, someone wants him dead.
Ness has always believed in the system. However, his faith is tested when he gets to transport a wrongfully convicted teen to state prison. Also, Capone plans to make sure that the kid doesn't make it there alive.
The younger brother of one of Capone's top men is arrested for murder. Will he snitch on Capone's organization or will he stay loyal to the family to the bitter end?
Son's illness and murder of a close friend get Capone to reevaluate his life of crime and the choices he's made.
Ness is trying to prove that Capone is blackmailing several important judges. However, he gets sidetracked when he falls for Cleo, one of Capone's callgirls.
Agent Paul Robbins must get to the captured Capone's hitman, before his friends do. He heads to a small western town where the criminal is being held.
Agent Robbins investigates Nitti's attempt to take over a railroad worker's union. Both him and Nitti are working against their bosses' orders on this one.
Capone has his hold over the businesses of a Native Americans tribe, but one of their younger members decides to rebel and hits one of Capone's banks. Ness' team tries to track the kid down first.
The prohibition is ending, so Capone decides it may be time to change his line of work and enter politics. He wants to become a congressman. Nitti, meanwhile, plans to set him up and take him out of the game for good.
Ness must find the one witness who can put Capone behind bars for good. Meanwhile, Capone's men, seeing that the end is near, decide to follow Nitti and drop Capone.