In the wake of Eamon Cunningham’s death, the Kinsella family is thriving. However a new threat rears its head when members of a Turkish cartel inform the Kinsellas that Eamon owed a them sizable debt – and since they killed him, the debt is now theirs. Elsewhere, Viking is released from prison intent on making trouble, Amanda suffers a personal tragedy, and a looming presence from inside the family returns.
　　The new season will see the Kinsellas at the top of the game in Dublin, but killing Eamon Cunningham has created as many problems as it solved. They have incurred the wrath of an enemy even more dangerous than him. And where once there were unbreakable bonds of blood and family, now there is only suspicion, distrust, and resentment. But the greatest threat to the family emerges from within: in the shape of a ruthless, bullying, agent of chaos. Fortunately, from positions of great adversity the boldest plans are often forged. And so it is with the Kinsellas.
　　Returning cast includes Charlie Cox (Daredevil), Clare Dunne (Herself), Aidan Gillen (Game of Thrones), Sam Keeley (Joe vs Carole), Emmett J. Scanlan (Peaky Blinders), Maria Doyle Kennedy (Outlander), and Yasmin Seky. Francis Magee also returns this season.

　　三名北爱尔兰首府贝尔法斯特的菜鸟警察要为正义而奋斗，却发现他们要对抗的是贩毒集团、准军事组织、卧底特务、当地社区，甚至是自己人。一场大规模的当地犯罪帮派调查行动戛然而止后，重重困难与危险问题随之浮现。是谁在保护这些罪犯？又为何要保护他们呢？