Garda Sergeant Jack Driscoll (Owen McDonnell) is back in action this autumn, this time in a new six part series. In the fourth series of this hugely popular and acclaimed drama serial childhood friendships, family ties, and romantic relationships are all tested to the limit. Some of the incidents which Jack must resolve include the violent death of a reclusive old man, an arson attack on a housing development, and a mysterious car crash, all of which draw him into dark and personally dangerous territory, as he has to probe the grey area between human failings and criminality.
Jack's personal life is complicated with the arrival of Brian (Matthew McNulty), an English cousin, who's visiting with his girlfriend, Gemma (Simone Lahbib). Brian's search for the father who abandoned him as a child opens old wounds for Eithne (Ruth McCabe) as a heartbreaking family secret is revealed.
Meantime at work Jack has to investigate the murder of an elderly recluse, Seamus Devlin. The suspect, Ruari, is a troubled teenager from Limerick who Jack is forced to take in hand as he gathers evidence against him.
When Brian Doyle (Matthew McNulty), Eithne's (Ruth McCabe) nephew, arrived from England in search of information on his long-lost father and his origins, Garda Sargeant Jack Driscoll (Owen McDonnell) was happy to help him dig in to the past. Having retraced the steps of this mysterious Uncle, Sean (Stephen Rea), it's a shock when Jack finds him alive and living in a local bail hostel. More worryingly he has uncovered evidence of his father, formerly the Garda Sergeant, having chased Sean out of town, away from his mother, and the Doyle land she has inherited.
Meanwhile, Jack is under pressure to establish who has inflicted the beating to his murder suspect, Ruari (Diarmuid Noyes) before the teenager tries to point the finger at the Gardai.
Programme Three: Between Two Fires: Part One
Garda Sargeant Jack O'Driscoll (Owen McDonell) arrives at a suspicious fire which his cousin's girlfriend, Gemma (Simone Lahbib) has photographed. Jack's old friends, the Kinsellas, reveal that they sold the stalled housing development to the new publican, Dennis Costello.
Jack discovers Finbarr (David Herlihy) has slipped Costello's (Sean McGinley) plans for a nightclub past him, fuelling his suspicions against the ex-Inspector. The body of Fiona Kinsella's cousin, Niamh, is discovered in the ruins and Jack promises her distraught husband, Ollie he will find her killer.
Gemma and Brian fall out over his plans to stake a claim to Eithne's (Ruth McCabe) land and when Jack and Gemma come together during his investigation the couple admit they are attracted to one another.
Jack finds photographic evidence that his old friend Killian Kinsella lied about not seeing the fire. Jack fears Killian did a deal with Costello to torch the development. Costello calls in Jack's old boss ex-Garda Sergeant Jim Dooley to deflect the evidence away from him.
Programme Four: Between Two Fires: Part Two
Having discovered that his friend Killian Kinsella (Denis Foley) lied to him about seeing the fire at the development he recently sold, Jack Driscoll (Owen McDonnell) waits for Killian's wife Fiona (Moya Farrelly) to go out before confronting him at their farm.
Gradually it emerges that Killian was having an affair with the woman who died in the fire and frequently arranged to meet her at the development under cover of the professional relationship. He had made an arrangement to meet that night but the lambing was so intense he couldn't get away. When he saw the flames at dawn, he thought Niamh had burnt the place down in fury. Jack tells Killian that Niamh didn't start the fire, and asks whether Fiona knew about their affair.
Back at home tension continues to develop between Brian (Matthew McNulty) and Gemma (Simone Lahbib). Jack is increasingly attracted to her but with a growing family rift over the land, the situation is becoming ever more complicated.
It is not helped by the arrival of Jack's arch enemy Jim Dooley(Conor Mullen), the husband of his old flame Maura Dooley. He is here to investigate the fire on behalf of the insurance company, but Jack deeply distrusts him and his suspicions prove to be well founded.
Faced with tough decisions about his personal life, a difficult case to investigate and uncertainty as to who he can trust, Jack is under pressure.
Programme Five: A Cold Heaven
Following a car accident, Garda Jack Driscoll (Owen McDonnell) is convinced Mairead O'Sullivan (Charlie Murphy), the teenager who claims to have been at the wheel, is covering for her Dublin boyfriend, James Kerrigan (Killian Scott). Further investigation reveals a darker truth as Jack uncovers evidence that Kerrigan has groomed Mairead to be a prostitute. Jack cultivates his friendship with Mairead finally persuading her to confess to her parents, and to turn James in to the law.
Jack evicts his cousin Brian (Matthew McNulty) from his mother's home, while Gemma (Simone Lahbib) struggles to reconcile her burgeoning romance with Jack with the confidential nature of his work. A bid to make peace with her ex-boyfriend, Brian, backfires and Jack ends up punching Brian.
Costello (Sean McGinley) puts the screws on Finbarr (David Herlihy) to repay his debts and when he witnesses the aftermath of Jack's violence, he realises he finally has the means to rid himself of his rival. Costello tells Finbarr that Jack will inevitably be expelled from the Guards.
Garda Jack Driscoll - Owen McDonnell
Eithne Driscoll - Ruth McCabe
Finbarr - David Herlihy
Sean Doyle - Stephen Rea
Gemma - Simone Lahbib
Brian Doyle - Matthew McNulty
Denis Costello - Sean McGinley
Louise Mullins - Úna Kavanagh
Pat McGlinchy - Barry Barnes
Ruari - Diarmuid Noyes