The story lines are darker - Jim Fenner being sexually harassed by the new gay Governing Governor, Neil Grayling. However, some more serious storylines included domestic violence within the relationship of Di Barker and Barry Pearce and teenage junkie Buki Lester's battle for the right to see her disabled son, Lennox. The fourth series ends with the prison library being obliterated as part of an escape plan by the devious Snowball Merriman, resulting in a fire that left Governor Grayling and several inmates trapped and fighting for their lives.

Episode 1 - Fight Or Flight
Virginia is dead - but who is responsible? Evidence points to Yvonne who takes drastic measures. Shell and Denny have escaped arrest in Spain but their fate is still uncertain
Episode 2 - Unholy Alliances
New governor, Neil Grayling, arrives at Larkhall and is determined to make his mark. He is unimpressed with Karen and starts to look for a new wing governor - surely not Fenner?
Episode 3 - Behind Closed Doors
Fenner is horrified to learn that Yvonne didn't murder Virginia and realising the real culprit forces him and Yvonne into an uneasy alliance
Episode 4 - Fait Accompli
Denny arrives back on G-Wing disappointed to learn that she still has her old enemy Bodybag to contend with
Episode 5 - Only The Lonely
Denny and Shaz are back together and true to form. Neil continues to make himself unpopular - does he really have the prisoners' interests at heart or is this a personal vendetta against Karen?
Episode 6 - Sweet Sixteen
Julie J is distraught to find her daughter on G-Wing. Buki is rescued from the escape tunnel at the last minute but has to face the wrath of Shaz and Denny
Episode 7 - Pillow Talk
Fenner finally realises that his boss's interest in him extends far beyond the professional. Shaz and Denny find another opportunity to humiliate Buki but begin to push too far
Episode 8 - Prison Issue
Buki can no longer cope with the bullying and harms herself, although more seriously than she intended. Outraged, Yvonne wants to see that justice is done
Episode 9 - Baby On Board
Yvonne and Maxi finally come to blows resulting in drastic consequences. G-Wing's tiniest inmate arrives when Crystal gives birth to baby Zandra on the floor of her cell
Episode 10 - Family Matters
Karen is furious after Fenner assaults her but realises that involving the police will be futile when the whole story comes out
Episode 11 - Battle Lines
Fenner is back in uniform and Neil is in dire need of a new governor. Karen turns down the job which means that there is only one candidate left - Hollamby!
Episode 12 - Appearances Sake
Cassie and Roisin's relationship deteriorates further especially as they both have their eyes on Yvonne. Yvonne herself is delighted when her estranged son visits her
Episode 13 - True Colours
The departure of Shaz has left a vacant cell on G-Wing, though it is immediately filled b