It’s Christmas Eve on G-Wing and as a chilling wind whips around Larkhall and the worried POs gather around to watch the weather forecast, a disturbing new inmate, Miranda Miles, steps off the van. As the snow begins to fall, Hollamby is looking forward to the end of her shift, the last thing she needs is a van full of inmates to deal with, especially when one of them turns out to be a completely cured Julie J. Then there’s the fact that Miranda has arrived without paperwork. But with the bad weather closing in and the phone lines down, it looks like she’s at Larkhall to stay. Without a warrant or anything to say who Miranda is, Neil wants her to be kept on the reception wing. Joy overrules him and insists that Miranda be given a cell on G-Wing.

Joy loves Christmas and is determined to get everyone, staff and inmates alike, involved in the festivities whether they like it or not. Prison Chaplain, Christy MacKay, is delighted to assist in Joy’s quest to bring a bit of seasonal cheer to Larkhall and looks on proudly as she dons her fancy dress outfit. Meanwhile, Neil is already in a bad mood because it looks like the weather is going to prevent him from joining Bobby Hollamby in the sun, and it is with great reluctance that he changes into his own Sherlock Holmes outfit. Hollamby is also in a ‘bag humbug’ type of mood, but given that her outfit is a completely unflattering Dickensian combo, it’s hardly surprising.

On the wing, Sheena is struggling to talk a cynical Pat into attending the carol service while Janine, Tina, Arun, and Darlene assemble for a last minute rehearsal of the G-Wing pantomime, ‘Snow Black’. Desperately missing her best friend, Julie S puts a brave face on and is temporarily cheered by the arrival of a vast Christmas tree. Phyl and Bev are also full of good spirits—brandy, gin, and vodka that it—smuggled into them inside a Christmas hamper from their good friend Oliver.

Julie S is thrilled when she discovers that Julie J has been allowed to return to Larkhall. But as she soon discovers, her best friend is still haunted by the memory of Fenner and is convinced that she can see him lurking around the landings. Terrified that Julie J’s visions will see her carted off to the loony bin again, Julie S manages to calm her down. Di is also delighted when she learns of Julie J’s return. Now that she’s mentally fit again, she can make a statement confessing to Fenner’s murder. However, Di’s dreams of being released before New Year are scuppered when it becomes evident that Julie J has no recollection of her previous confession.

At a loose end, Natalie decides to bolster her self-esteem with a spot of bullying and demands to know if Miranda has brought her a ‘present’. Seemingly totally unfazed by Natalie, Miranda calmly introduces herself as ‘Satan’s daughter’ and then uncrutches a full set of Russian Matryoskha dolls. Any further bullying is put on hold by the arrival of Spiers. In the mood for some Christmas kinkiness, he takes Natalie to the chapel, blindfolds her and then forces her to kneel down on the altar. In search of the carol sheets, Christy walks in on Spiers and Natalie. She sees straight through his panicked attempt at a logical explanation and tells him that she’ll be informing Joy of what she has witness as soon as she is able.

It’s time for the carol service, but just as all of the inmates and POs begin to sing, a vicious gust of icy wind blows an exterior door open and sends pots, pans, and the knife cupboard crashing around the servery. Then, the lights go out and the whole wing goes into immediate panic—all except Miranda that it—she rather likes the dark. With the electricity off and the back-up generator broken, Joy is at a complete loss for what to do—she’s got no chance of getting hold of an electrician before New Year. Luckily, Neil has a plan and before long, Phyl and Hollamby are inching their way into the dark cellars on a quest to repair the generator. But when squeamish Hollamby discovers a rat crawling up her bloomers, she faints and falls against the generator room door, trapping Phyl inside.

Feeling the cold, Julie J returns to her cell for a cardigan and finds Fenner sitting on her bunk, expelling lungfuls of icy breath. When he stands and begins to walk towards her, Julie J begins to scream. G-Wing’s inmates and POs sprint up to G2. Despite Julie S’s attempts to shut her friend up, everyone hears her claiming to have seen Fenner. Nonchalantly, Miranda walks into the cell and confirms Julie J’s story—she saw Fenner too! Despite Neil and Joy’s attempts to convince the inmates that there is no such thing as ghosts, the dark and spooky atmosphere on the wing combined with Julie J’s claims that Fenner is still alive soon works the inmates up into a state of hysteria. Even Christy is sure that she can sense something “evil and unnatural” on the wing and tries to persuade Joy to allow her to perform an exorcism. But it seems that something more serious may be on the verge of happening—more than one knife has disappeared from the broken knife cupboard.

Thanks to Phyl, the generator is working and the lights are back on, but even so, Joy is finding it hard to quell the sense of panic on the wing. In desperation, and despite Neil’s incredulous objections, she allows Christy to go ahead with the exorcism. As Christy performs the ritual and sprinkles holy water around the wing, Miranda steps forward. Recognising her as the evil presence, Christy douses Miranda in holy water. Miranda responds by cursing and bleeding from the mouth. Grabbing the cup of holy water, Miranda drinks from it and then spits a mixture of blood and water in the Chaplain’s face. Still refusing to allow Joy to intervene, Christy grabs a crucifix and manages to calm Miranda down, seemingly banishing the evil spirit in the process.

Spiers can see his career spiralling down the toilet before him and so he has no choice but to give Natalie the go-ahead to put Christy out of action. Natalie goes to speak to Miranda. With the screws busy watching the inmates involved in a mass snowball fight outside, there’s no one to witness her giving Miranda a knife stolen from the cupboard. As Natalie joins the other inmates outside, Miranda enters the staff showers and stabs Christy to death with the wooden crucifix that the Chaplain left in her cell.

As a terrified Hollamby discovers Christie’s body, Julie J sees Fenner appear in her cell. She reaches for a knife stolen from the servery and tries to defend herself, but after a struggle, stabs herself in the stomach. As the doctor works on Julie J, Miranda is discovered covered in Christy’s blood and surrounded by wood shavings and the knife she used to sharpen the crucifix. Later, when Neil and Joy access Miranda’s paperwork, they discover that she was in the process of being transferred to a secure mental hospital after killing a PO and was left at Larkhall by mistake. It is clear that Joy blames herself for Christy’s death.

Julie J is very lucky. Despite the depth of the wound in her stomach, the injury isn’t life threatening. Initially relieved when she hears that Julie J is going to be okay, Julie S is furious when she finds out that she hasn’t been taking the pills that had been prescribed to combat her bipolar disorder because they were making her put on weight. Julie S makes her promise that she’ll resume taking her medication, even if her bottom does swell up to the “size of Clapham”.

It’s Christmas Day and Sheena wakes Pat with a present—a letter from the Registry Office. Sheena has asked someone to visit the prison so that they can initiate proceedings to officially register their relationship. Pat is over the moon, especially when Sheena asks her if she’s prepared to become Dylan’s legal guardian and his second mum.

The traumatic events of Christmas Eve are put aside as the staff and inmates gather on the wing to enjoy the World Premiere of ‘Snow Black’. Now that Julie J is back on her medication, has Fenner’s evil spirit been banished from G-Wing for good?