Melbourne standover men Brian and Les Kane have ventured into unfamiliar territory by providing protection for Bob Trimbole's Melbourne heroin dealers. But things turn sour when dealer Wayne Robb is robbed of $200,000 cash on the Kane's turf. The Kane's suspect it was Vinnie Mikkelsen and Laurie Prendergast, two of Ray Chuck's mates from the Great Bookie Robbery.

Allison questions her role in the Mr Asia syndicate after her life is threatened by a corrupt Federal Narcotics Bureau agent. Colourful racing identity, George Freeman, takes extreme action after police raid his illegal casinos. The Mr Asia syndicate suffers a major setback when a drug courier is arrested.

Aussie Bob Trimbole is pressured to arrange a gangland hit on his friend and colleague, Allison Dine. Meanwhile, paranoid and living in exile in the UK, Terry Clark must terminate his relationship with "Mr Asia". Also, George Freeman is determined to get revenge on his would be assassin, and aspiring hitman "Mr Rent-a-kill" gets his big break.

Terry Clark's drug empire starts to unravel when he is arrested for murder in the UK, while Allison is arrested by the FBI and becomes a star witness against organised crime. With his heroin supplies drying up, Aussie Bob plans Australia's biggest ever cannabis smuggling operation. Meanwhile, the Federal Police have a major win against corruption at the Narcotics Bureau.

In the series finale of Underbelly, Chris "Mr Rent-a-Kill" Flannery becomes a victim of his own success. But who would dare order a hit on Australia's most dangerous hit man?

The Melbourne gangland wars start the night the gangster Alphonse Gangitano, "The Black Prince of Lygon Street", and one of the legendary Carlton Crew gang, murders a low-life crim named Greg Workman at a St Kilda party for the sheer hell of it. The charming gangster Alphonse gets away with the murder by convincing two witnesses not to testify but the killing sets the tone for the mayhem that will follow, and sets Alphonse himself on a path to self-destruction.

Convinced that Jason Moran was also involved in the nightclub assault, Steve Owens tricks Jason's driver Carl Williams into revealing that he did indeed ferry Jason to and from the scene. Carl Williams takes the first steps towards building his own empire. The police are determined to crack the "Carlton Crew" crime gang.

Brothers Jason and Mark Moran decide that the Carlton Crew needs to be pulled into the 21st Century. The Moran brothers do a deadly deal to expand their empire while Carl Williams starts his illegal dealings - in direct competition with Jason Moran. As tensions increase, the police convince a young mother to testify in a murder trial - with tragic results. Carl Williams meets the love of his life, Roberta.

Carl Williams is caught red-handed whilst double-crossing the fearsome Moran brothers; the underworld is in an uproar over the mystery source of cheap drugs; a kidnap goes terribly wrong, from farce to disaster, when nobody wants to pay the victim's ransom, which only adds to the tension.

Carl Williams begins his deadly revenge on the crime-controlling Carlton Crew, and tries to increase his ever-expanding grip over the Melbourne crime world; whilst Jason Moran is in jail, his brother Mark takes control of the family business; Detective Steve Owen is determined to prove an underworld murder.

Lewis Moran hires Benji Veniaman to execute his son's, Mark Moran's killer. Subsequently, Veniamen is insulted by the Carton Crew and forms a dangerous alliance with their unpredictable rival Carl Williams; Steve and Jacqui's police instincts are tested when they try to disprove a murderer's alibi; when a criminal is shot dead multiple times, the Police realise there's a monster on the loose.

With their men in jail or dead, the women who love gangsters try to get on with their lives. With Carl Williams in prison, a rival crime boss tries to undermine his empire. A young lawyer falls for her client, a convicted killer linked to the Carlton Crew. The police make a major breakthrough in identifying the mystery hitman they know only as “Benji".

Amid growing public unrest, the police establish Task Force Purana to combat the gangland war. Loan shark Mario Condello faces his own financial crisis, which he solves with brutal efficiency. Bitter rivals Carl Williams and Jason Moran take out contracts on each other’s life. Taskforce Purana detectives are furious when police corruption derails their investigations.

Jason Moran returns from self-imposed exile, determined to destroy his rival Carl Williams; death stalks a children's football match; Taskforce Purana finally gets the resources it needs to defeat the criminals; Benji is under constant police surveillance, so Carl is forced to find a new accomplice; Carl and Roberta celebrate their daughter's christening with a lavish party.

Carl Williams is now the undisputed king of the underworld, confident he can get away with murder; the police make the first major breakthrough in their investigations, but they may be too late to prevent another death; Benji's relationship with Carl and Roberta becomes increasingly personal.

Carl uses his high media profile to accuse Detective Steve Owen of corruption; Graham "Munster" Kinniburgh is gunned down and Mick Gatto tries to convince Carl Williams to end the gangland war; "Benji" Veniamin agrees to kill his former mentor Mick Gatto, but it's Gatto who lives to tell the tale; Carl and Roberta are rocked by the death of their closest friend.

Lewis Caine vows to avenge his best mate Benji's death, but can't trust his new colleagues; lawyer Zarah Garde-Wilson's plans for a romantic future are shattered when her lover is killed; Taskforce Purana finally gets the upper hand in their investigations.

Detective Steve Owen finally gets enough evidence to arrest Carl Williams for murder. After nine years the gangland war is over.

In the mid 1970s, Kiwi charmer Terry Clark and "Aussie" Bob Trimbole form a deadly alliance that will change the face of Australian crime forever.

In episode seven of Underbelly, Terry decides to franchise his crime empire and expand into the UK market. Aussie Bob goes to extreme lengths to buy out Terry's share of the Organisation.

The Federal Police prepare to arrest crime boss and cancer sufferer Aussie Bob Trimbole. But a mole within the Feds threatens to create havoc with their investigation. Also, Alison Dine testifies at a coroner's inquest, and blows the lid on the Mr Asia syndicate.

A naive young Kiwi, Allison Dine, is swept off her feet by Terry Clark, becoming his lover, and most inventive drug courier.

Australia's most dangerous hitman, Chris "Mr Rent-a-Kill" Flannery, moves to Sydney to build his deadly reputation. Terry Clark's UK murder trial reaches a sensational climax, but can Allison testify against her former lover? Meanwhile, Aussie Bob gets involved in arms smuggling for the IRA.

When a prisoner is abducted and murdered while on day-release, police embark on a massive man-hunt to find the killers. The 10-year investigation leads them to a ruthless underworld boss who is totally invisible to the police and the legitimate world.

Brian Kane plans Australia's most audacious gangland murder to avenge the death of his brother Les. Meanwhile, Ray Chuck forms an alliance with Mark "Chopper" Read in a Melbourne jail. Also, aspiring hitman Chris Flannery finally gets his big break and Terry's growing drug empire is under threat from problems in Australia and Singapore.