"Survivors" is the 992nd episode of Casualty and the 31st episode of the 30th series. It was preceded by "Hopelessly Addicted" and followed by "A Clear Conscience". The episode was directed by Lee Haven Jones and written by Claire Miller.
Rita is at her nursing best while she attends to a young woman calling herself Jane Eyre, who's been involved in a traffic accident. But Rita's left in shock when Jane's boyfriend is later admitted and it turns out to be Rita's ex-husband, Mark, who destroyed their relationship when he had a sexual relationship with one of his underage students. Shock then turns to horror when Rita discovers eighteen-year-old Jane's real name is Fiona, and she's the pupil former teacher, Mark had his paedophilic affair with.
Iain Dean spots Jez leaving the house kissing a guy, leaving him very confused. Throughout the day when Jez continues to flirt with girls, Iain tries to hint to him that he doesn't have to hide his true sexuality, but this is all lost on Jez. When he realises what Iain thinks, he decides to mess with Iain even further by flirting with him.
Dylan and Robyn work together in treating sisters, one of whom has a suspected case of cyanide poisoning and the other is planning to have a mastectomy to reduce her risk of cancer. Although initially putting both of their illnesses down to food poisoning, it eventually becomes evident that one of them has cyanide poisoning as a result of ingesting fruit seeds containing deadly doses if eaten in high amounts.
Meanwhile, Rita continues to treat Fiona and it later transpires that she's pregnant. However, the fetus is found to be growing outside the womb and Lily tells her that the pregnancy hasn't been a success. In anger, Fiona locks herself in Connie's office and agrees only to come out if she can speak to Rita. Rita speaks to her, and Fiona voices her concerns that if she were to break up with Mark, he would go back to being seen as a paedophile as they're no longer together. Rita indirectly hints for her to break up with Mark but just as they finish the conversation, Fiona's condition worsens and she's rushed out.
Mercedes comes into the ED looking for Jacob, trying to get her drugs back, but he can’t help her. She spots Big Mac stealing from the pharmacy and takes the opportunity to blackmail him to steal drugs for her. He eventually volunteers to go to the pharmacy for Rita to pick up medication on a prescription for a patient, but Big Mac instead pockets the drugs and gives some to Mercedes. Outside the ED, she tells him that anytime he needs something to let her know. Also, Zoe tells Connie that she's planning on leaving Holby, but also tells her not to tell anyone.
At the end of the day, Rita is confronted by an angry Mark who has just been dumped by Fiona. He blames her, saying that it's just that she's jealous and couldn't stand to see them together. Rita dismisses the allegations, but Mark continues to blame her and calls her cold and heartless. Rita fails to notify Iain about any of it due to the complicity of the explanation.