Underbelly

In the debut double episode set in 1976, drug dealers Terry Clark and Robert Trimbole form a partnership in the heroin trade. Trimbole orders a hit on local Griffith anti-drugs campaigner Donald Mackay. In Melbourne, Detective Liz Cruickshank is tipped off about the hit by standover man Les Kane, but her boss Inspector Messina doubts Kane's story.

Detective Warwick Mobbs suspects police corruption as his efforts to solve Mackay's murder are constantly frustrated. In the meantime, Melbourne armed robber Chuck Bennett masterminds the Great Bookie Robbery but snubs Kane and his brother Brian, provoking a turf war.

Allison Dine arrives in Sydney from New Zealand and begins working for Clark as a drug courier, soon becoming his lover. Mobbs endeavours to investigate George Freeman and shut down his illegal bookmaking activities, but is tharwted by high-level police corruption and reassigned to Wagga Wagga. Clark murders drug mule Pommy Lewis.

The Kanes are now protectors for Trimbole's dealers in Melbourne. When two members of Bennett's gang steal from one of the dealers, the Kanes use it as an excuse for revenge. After several confrontations, Bennett and his associates machine-gun Les Kane to death in his home in front of his family in 1978. In Sydney, Allison devises a new way to smuggle Clark's drugs.

Chuck Bennett goes on trial for Les Kane's death, but in the absence of a body is acquitted. Brian Kane hires Chris Flannery to kill Bennett, but Bennett is immediately re-arrested on another charge. Wearing a disguise, Kane murders Bennett as he is taken to court. In Sydney, Terry and Allison's affair cools and Trimbole accidentally gets George Freeman arrested.

Clark is arrested on a minor charge in Queensland and extradited to New Zealand to face drug charges. His couriers the Wilsons crack under police pressure and the body of Pommy Lewis is discovered. After being acquitted, Clark returns to Australia. Trimbole convinces him to have the Wilsons killed.

Terry decides to franchise his crime empire and expand into the UK market. Allison is promoted to a major role in the organisation.

The Federal police team up with the Victorians to target the drug trade, while NSW's corrupt cops plan to seize control of organised crime. Allison questions her role in the syndicate after she is threatened by a corrupt Federal Narcotics Bureau agent. Meanwhile, George Freeman takes extreme action after police raid his illegal casinos and is shot outside his home.

Clark, paranoid and living in exile in the UK, pressures Trimbole to take out a contract on Allison. Trimbole hires Chris Flannery but Allison is arrested before he can act. She flees to the US with Trimbole's help. Meanwhile, Clark has his major supplier Marty Johnstone murdered when a deal goes wrong, and Freeman's would-be assassin is executed.

Clark is arrested in the UK for Johnstone's murder. Allison is arrested by the FBI and turns star witness against the syndicate. With the heroin money drying up Trimbole plans to import an enormous cannabis shipment. The Feds see Brian Alexander as a weak link in the chain and lean on him.

The inquest into the deaths of the Wilsons commences. Trimbole learns he has cancer. As Allison's evidence inplicates everyone, a Royal Commission is convened and the Federal Narcotics Bureau is disbanded. Freeman tips off Trimbole, who flees overseas. Alexander is murdered by the cops on Freeman's payroll.

Clark is found guilty of murder and jailed. Trimbole uses Nick Paltos to bring his massive drug shipment to Australia. Chris Flannery moves to Sydney and links up with George Freeman, killing people almost at will to prove himself.

Terry Clark dies of a heart attack in prison. A dying Trimbole is arrested in Ireland, then flees to Spain after being released without charge. Freeman's police allies convince him that Flannery has become too dangerous to live. Paltos is arrested for trafficking but refuses to talk. Trimbole dies in a Spanish hospital.