"Hello, I Must Be Going" is the 995th episode of Casualty and the 34th episode of the 30th series. It was preceded by "Tangled Webs We Weave" and followed by "Chain Reaction". The episode was directed by Steve Hughes and written by Jeff Povey. It features the first appearance of consultant Elle Gardner, portrayed by Jaye Griffiths. In addition, the episode features the final appearance of long running character Zoe Hanna portrayed by Sunetra Sarker, who joined the show in December 2007.
In addition to the regular cast changes, recurring guest character Mercedes Christie, portrayed by Hannah Spearritt makes her final appearance in this episode, having first appeared in the January 2016 episode "Shame". It also marks the final appearance of her partner Vince and her drug dealing boss, Shelle.
The first half of the episode is split into two storylines; the present and flashbacks from earlier in the day. The timelines eventually join midway through the episode, so the story continued in the present.
The episode opens with a scene of Zoe and Elle in a storage type room with a badly injured Vince, and Shelle with a knife in her hand threatening them. The first half of the episode flashes from these scenes to flashbacks which follow the events leading up to those moments. Midway through, the flashbacks catch up to the part of the story where Zoe and Elle are in the room with Shelle just as Max enters, and the story continues from there as normal.
Zoe and Max wake up after spending the night together, and she tells him that she handed in her notice a month ago and is leaving Holby to go and work in Michigan later that day. She turns up at the ED for her shift, and tells Max she is ready to say goodbye to everyone, but that she's only told Connie and the board about her departure.
Meanwhile, Elle Gardner leaves her house in a rush, due to start her first shift at Holby ED. She attempts to wake her three teenage sons on the way out, but is unsuccessful. Inconveniently, she is caught up in traffic, but eventually decides to take a shortcut through the park, something not strictly allowed. Meanwhile Connie and Hanssen make a bet on how long it will take for Elle to arrive, as Connie isn't happy about her lateness.
Meanwhile Vince receives a call from Mercedes who tells him that Shelle is coming after her at the ED. He runs through the park to get to the hospital, but Elle Gardner hits him in her car when he runs into the road. She calls for an ambulance and although his inuries aren't serious, they decide to take him into the ED. Elle accompanies Iain and Jez in the ambulance back to the hospital. Once there, Vince runs over to Shelle who is waiting at the edge of the car park. She takes him into The Hope & Anchor which is empty, and shouts at him, threatening to hurt Mercedes due to the fact she's lost all her money because of them. Elle and Zoe follow her over, and shortly after Shelle badly injures Vince's arm with a knife and bashes his head against an arcade machine, knocking out some of his teeth. She tells Elle and Zoe to take him into another room which is separate from the rest of the pub.
Meanwhile outside the ED, Dylan assists in helping a man, Greg, who's turned up with his partner Joanna after she suspected he had a stroke. They bring him into the ED and they discover that he hadn't actually had a stroke, but whilst he's having a CT scan done, he actually has a stroke and is rushed back into resus. Meanwhile Max is confronted by Mercedes who expresses concern about the whereabouts of Vince following Shelle's threats. Max tells her he can't help and waits for Zoe outside the ED but she doesn't turn up. Robyn tries to convince Max to forget about her, as by this point Max had already told Robyn she was leaving. It soon transpires that Greg is having an affair with Joanna, who happens to be a good friend of his wife. She tells Robyn not to tell his wife she was there.
Iain receives multiple texts from Rita, and Jez begins to make him think he's in it too deep, and that Rita has become overly attached. Max asks Dylan of Zoe's whereabouts, and he tells him that he saw them heading in the direction of the pub. Max goes over there to find a patch of blood on the arcade machine, as well as more blood on the floor. He overhears Shelle's voice in another room and goes in to investigate.
Just as Max bursts through the door, Shelle goes to attack him but Zoe punches her in the face. In anger, Shelle turns around and stabs Zoe in the hand, leaving her with a bad wound. The police are called and Zoe and Elle accompany Vince into the ED whilst Vince is taken through for treatment. Max speaks to Zoe, and tells her that he is going to move to America with her. Elle is successful in saving Vince, despite Connie's initial doubts and concerns. Max tells Robyn about his plan to move to America with Zoe, but she discourages him, saying that he'll just get his heart broken again. Meanwhile Elle reveals to Zoe that she's spoken to the police and is looking at community service. Zoe later says goodbye to Dylan and tells him that she's leaving later that day to go to Michigan for a job offered to her by Nick Jordan.
Mercedes goes to see Vince who's recovering, and although he's not conscious she tells him about the pregnancy. Meanwhile, Robyn talks to Joanna and at the same time realises that she has to make sure Zoe won't hurt Max again. She goes and talks to Zoe, who promises her she won't break his heart again, but Robyn doesn't believe her, and Zoe is left wondering whether it's the right thing to do to bring Max with her to America. Back in reception, Charlie asks Zoe to let him look at her hand. Whilst examining her, he tells her that he has figured out that she's leaving as Connie wouldn't hire a new consultant without an old one leaving. Meanwhile Louise helps David in his attempts to become less shy in the ED and advises him to go to Robyn.
Zoe gets in a taxi outside the ED and leaves for the airport. She rings Max just before she leaves and tells him that she's going without him. Robyn watches her drive off and wonders if it's her fault that Zoe's leaving without Max and begins to reconsider and wonder whether it was the right thing to do. As Max is trying to contact Zoe outside the ED, Robyn drives up in her new car which only fits two people in, one behind each other. Max gets in the back and they drive off for the airport.
Back at the ED, Elle goes outside for a cigarette, a habit which she overcame years ago. She encounters Hanssen whom she appears to know from a previous encounter. Max catches up with Zoe just as she is about to pass through the gate, and he tells her that he wants to go with her. However, she tells him that she can't let him as she knows he will just get hurt again, and she says goodbye. Meanwhile Elle continues her chat with Hanssen, and he tells her that he would like to think she'd let him know if things didn't quite feel right in the ED, to which she agrees.
At the airport, Zoe goes through security when the buzzer goes off. She realises it's her name badge for Holby ED and takes it off, and puts it in the tray and tells the security guard she won't be needing it anymore as she goes through to the boarding lounge. Max arrives back at the ED, clearly emotional about the day's events.
Zoe's departure received mixed reactions from fans as a whole. Many were angry at the fact Zoe and Max didn't get a happy ending like many other couples from the past, but some praised her exit storyline for her as an individual. Alison Graham writing for the Radio Times said: "A bloodstained Zoe Hanna addresses the camera directly at the start of her valedictory story: "My day started so much better than this..." before a clock ticks loudly on the soundtrack and things go a bit slow motion. We know it's a bad last day for the doc."
After the episode aired, BBC Casualty's Facebook and Twitter pages posted a link to Zoe's departure video on the BBC website which feature highlights of Zoe's time whilst in the ED. This featured her relationships with Matt Strong, Nick Jordan and most recently Max Walker. It also featured some of her prominent storylines including when she slept with a fifteen year old boy without realising his age, and in series 27 when she worked to help some girls who had been the subject of genital mutilation.