"Thirty Years" is the 1015th episode of Casualty and the 11th episode of the 31st series. It was preceded by "Shock to the System" and followed by "About My Mother". The episode was directed by Paul Riordan and written by Kelly Jones.
Duffy prepares for the arrival of her daughter-in-law at the ED who's heavily pregnant with her son Peter's child. They arrive in the ED and Peter is surprised at how close Duffy is with Charlie considering she's married back in New Zealand. Shortly after, Tanya attempts to leave after catching sight of another patient, but she soon goes into labour and they're forced to stay a little longer.
Meanwhile Elle treats the other lady, Karen, who is suffering from liver problems due to past alcoholism. Charlie decides to bring up her file on the system after Duffy informs him of Tanya's strange behaviour earlier and it transpires that Karen is Tanya's mother. In the 90s, Tanya was taken away from Karen due to a lack of care and they'd been estranged ever since.
Elsewhere, a 15 year old boy, Rhys, is admitted after running away from an institution and having a seizure in the street. His mother follows shortly after, insisting that he have a brain operation which has a chance at making his seizure's almost non-existent. However, he decides not to have it and Dylan and Seb take his side, assuring him that no-one will force him into anything. Before long, the neurosurgeon is called down and it turns out to be Archie Grayling, Seb's father. He agrees with the boy's mother, Julie, that he should have the operation and a conflict of interest soon becomes apparent between the doctors. Lily informs Alicia that Archie is her type, and she encourages her to see if he's single.
Tanya decides to be transferred to St. James Hospital for the cesarean after all. Her and Peter board the ambulance, just as Karen emerges outside the ED threatening to kill herself if Tanya doesn't make contact with her. As Iain shuts the ambulance, Karen grabs the keys and throws them down a drain leaving Peter and Tanya trapped in the ambulance with Jez, who's unable to unlock it from the inside. Eventually Charlie breaks the window and him and Duffy climb in to assist. At first, it doesn't look good but the fire crews soon arrive just after Tanya gives birth to a baby girl. They're both taken inside as a relieved Duffy looks on. In reception, Alicia asks Archie on a date for Lily which he agrees.
Meanwhile, Rhys suffers from a seizure and Seb fails to quickly take action, something which displeases Dylan. However, Dylan soon catches onto the fact that Seb's father is pressuring him which is ultimately hindering his patient care. Seb has a chat to Rhys and tries to get him to listen to his mum and have the surgery as it's best which he does. Seb fixes up the relatives room with a romantic dinner table for Rhys and his date that he was meeting. Towards the end of the shift, Archie informs Seb that he has organised for Elle to be his mentor and that it's not negotiable. Seb tells him that he's staying with Dylan leaving Archie angry. Shortly after, Lily arrives ready to go on the date with Archie.
Charlie and Duffy join Peter and Tanya with their new baby girl. It's not long before Karen arrives wanting to give a gift to Tanya. Although Tanya tells her that she doesn't want her to beg for forgiveness, she says she wants her to attend her AA meetings which she agrees to. The drama of the day results in Duffy going into a storage cupboard and breaking down in tears. After she rushes out of the room, Peter gives Charlie an old picture of him with Duffy and tells him that she always used to look at the picture when she was feeling down.
Charlie joins Duffy in the cupboard and they reflect on the last 30 years working together. They give into the temptation and kiss, following Duffy deciding that her marriage isn't working out.