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.

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.

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.

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'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...

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

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.

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.

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.

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.

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.

Nidge is summoned back to Spain, where Terence demands a terrible price for his continued support, while Siobhan and Moynihan reach an unholy deal of their own.