As the shipment of drugs arrives at Dublin port, the deadly game of cat and mouse between Nidge and Moynihan reaches its climax.

Darren Tracey skipped Dublin when a gun was found in his house and he’s been living the past year in Spain, but he decides to risk it and come back to Dublin. He’s homesick and a party for his brother’s release from prison is the perfect excuse. It’s only for the weekend but sometimes life is full of surprises - especially if you and your friends are in gangland.

Darren is tracking Jimmy Byrne, the chief suspect in the gangland killing. But in the meantime he needs to work and he soon finds himself slipping back into working for gangland boss John Boy Power. In a world of paranoia and betrayal will Darren be able to keep his wits about him, kill Jimmy Byrne and find love again with Rosie?

The gang come back from Nidge’s stag party in Prague to learn that Jimmy Byrne is back in town. His friends think Darren should kill him as soon as, but Darren’s not so sure. Tension mounts as Darren needs to make decisions not only about whether to follow through on his suspicions, but about what he should do about his feelings for childhood sweetheart Rosie. As Darren grows closer to uncovering the truth, tensions and suspicions rise among the gang. Darren in particular faces difficult decisions about his feelings for Rosie, his future and his loyalties.

In debt to loan shark Fran, gang footsoldier Darren finds he has no choice other than to turn back to his former mentor, northside kingpin John Boy Power. Under pressure from the cops and doing way too much cocaine, John Boy is becoming paranoid and erratic. John Boy agrees to take on Darren’s debt in return for absolute loyalty – the deal with the Devil done, Darren is back on the team...

Nidge coerces his dentist into cooperating with him, unaware that Detective Inspector Moynihan is setting up a complex undercover operation to track and ultimately bring him down.

Disaster strikes the gang as a drug mixing factory is busted by the gardai. John Boy blames Stumpy who he believes sold them out. Darren, desperate to get out of the game, robs an ATM machine and makes a downpayment to John Boy against the debt he owes. John Boy, however, wants Stumpy taken care of and he wants Darren to be the one to deal with it.

When a container of drugs is busted at the docks, John Boy decides to double cross Fran on their deal. Fran retaliates against John Boy. John Boy is furious and orders Nidge to pipe bomb Fran's house leaving Fran determined that the escalating gang war will not end until he has revenge.

Fran, still afraid that he could go down for the tiger kidnapping, lashes out looking for someone to blame. Resulting in a serious challenge to Nidge's authority.

Nidge's preparations for the import operation are disturbed by an unwelcome encounter with a ghost from his past, and Nidge will do anything to prevent a terrible truth getting out. Isolated and increasingly paranoid, Nidge finds solace in his relationship with Janet and fails to notice that Moynihan and his undercover team are closing in on one of the conspirators...

The crew are in festive spirits as Trish has the baby on Christmas Eve, while Rosie has come back to Dublin and Darren falls in love with her all over again. However the gang war is still raging, and John Boy orders Tommy – already caught between his friendship with Debbie and his worries about Siobhan’s money runs – to kill Fran. The hit goes wrong, and someone else becomes fatally caught up in the aftermath.

Dublin gang boss Nidge has been blooded and has proved his mettle. He has killed friend and foe to become King. But the throne is a dark and lonely place.

Moynihan's surveillance operation closes in on Nidge and Andrew's dummy run bringing in a shipment of mixing agent, while Fran plots a gruesome revenge.

Nidge sets out to persuade Dano that he had nothing to do with his father's disappearance but a scapegoat must be found. Nidge turns to ever faithful Darren for help.

Nidge struggles to allay Dano's suspicions when his secret threatens to get out as Siobhan and Elmo, for different reasons, start to talk.

After almost losing everything to D.I. Moynihan’s sting operation, Nidge travels to Spain to negotiate with a wholesale supplier for a new drugs shipment. Meanwhile, Patrick has returned to Dublin to exact revenge, and tensions between Fran and Nidge reach boiling point.

Fran is banged up in prison but he and Nidge both still conspire to have each other killed, while Siobhan finds her dangerous drug fuelled double life is spiralling out of control.

As Nidge and Trish’s wedding day arrives, gangwar is breaking out. John Boy and Hughie generate new plans and new recruits. Who will be with them? Darren is worried about John Boy and Hughie’s volatility, not just for himself but for his sister Mary and the kids. Relations between John Boy and Darren come to a head. Darren decides that it is in everyone’s interest that he heads for London. Can he end the war before he leaves?

Nidge swiftly fills the power vacuum and gets the gang back to business as usual. Rosie has realised what her lover has become, and Darren is devastated when she breaks up with him. Meanwhile Mary finally realises the extent of Luke's psychosis as she finds him lurking in her bedroom at night.

Pressure builds on Nidge as the leaders of Dano's organisation send an inquisitor down from the north to thwart him, and matters only get worse as his lies start to catch up with him.

As both Dano and the Gardaí begin to put the puzzle together, what can Nidge do to stay ahead and stay alive?

In the aftermath of Pauley’s death Siobhan must face her most terrifying opponent yet as Terence May flies in from Spain to lay his nephew to rest—and to find the truth.

As tensions come to a head the gang threatens to implode: Luke's obsession with Mary is becoming more dangerous, while Siobhan's panic attack at the airport could get Tommy killed. Paranoid John Boy finally tips over the edge of sanity when he finds Debbie taking heroin.

With Pauley’s help, Nidge is back in business and arrangements are made for the first shipment under the new deal. Meanwhile Moynihan wrestles with a labyrinthine Garda bureaucracy.

Nidge uses Scotty as a driver on a new job, while Siobhan learns Tommy will soon wake from his coma and finds herself caught between her quest for revenge and her love for Pauley.