Single-Handed - Season 4

The body of elderly recluse Seamus Devlin is discovered dead in a field and the initial charge is to Ruairi, a troubled teenager, who is staying at a remote youth facility. Jack is forced to keep watch on him as he gathers evidence on the death. Meanwhile, a long-lost cousin Brian and his girlfriend Gemma opens up new wounds for Jack's mother and the discovery of an uncle Jack never knew existed - a victim of the now derelict and violent industrial school for young offenders.

Jack continues his investigation into the death of Seamus Devlin and discovers a link between him and his newly found Uncle Sean going back to his uncle's days in St. Augusta's Industrial School. Meanwhile, Dennis Costello plans a major redevelopment of his pub which won't please Jack. Elsewhere, Brian considers staying on and renting after Dennis tells him that his father inherited land in the area which is now his.

Jack investigates the suspicious fire of an unfinished house which belonged to his friend Killian Kinsella. Killian informs him that he sold the house to Dennis Costello some weeks previously. Shortly afterwards the body of Killian's sister-in-law Niamh Duffy is found dead in the burnt out house. Jack suspects that Dennis had a hand in the fire and sets out to prove what happened. Meanwhile, Jack kisses his cousin's girlfriend Gemma and also finds out that Finbarr slipped plans for Dennis's nightclub past him and he is far from pleased. Elsewhere, Dennis calls in Jack's old boss to help him deflect evidence of the fire away from him.

Jack continues to find the person he believes torched Dennis Costello's abandoned house but finds himself thwarted every which way by both Costello and his former boss Jim Dooley. But is Jack looking in the right direction? Meanwhile, Gemma breaks up with Brian and he takes revenge by attacking Jack and then changing the locks on Eithne's home barring her entry.

Jack starts an affair with his cousin's ex-fiancée Gemma just as he begins an investigation into a prostitution ring led by Dubliner James Kerrigan who has managed to lure local teenager Mairead O'Sullivan into the ring also. An out of control Brian attacks Gemma prompting Jack to hit Brian but his attack gives Dennis Costello the ammunition he has been looking for in trying to get rid of Jack. Elsewhere, a broke Finbarr applies for a loan to the bank.

Jack is suspended by Inspector O'Kane pending his investigation into the assault charges on his cousin Brian. Dennis puts the thumbscrews into Finbarr now that he is acting Sergeant but is Finbarr finally getting wise to Dennis's tricks. Meanwhile, Mairead O'Sullivan overdoses after she refuses to give her statement to anyone but Jack. At the hospital James Kerrigan takes advantage of Mairead and brings her back to his house and forces her to resume her prostitution role. Although suspended he works with Mairead's dad to get Mairead back.