"The Best Day of My Life" is the 998th episode of Casualty and the 37th episode of the 30th series. It was preceded by "This Life" and followed by "You Make Me Sick". The episode was directed by Julie Edwards and written by Ben Ayrton and Jeff Povey. This episode was an hour in length in comparison to the regular duration of 50 minutes, with the additional ten minutes worth of material being written by Sarah Beeson and directed by Steve Hughes.
Henrik visits the ED after word has reached him that a patient who claims her drugs were stolen the previous week has gone to the press and an article will be printed about it the next day. He speaks with Connie about it and tells her up front that there's a thief and that they're going to want answers. However, Connie fails to take it seriously and tells him that people lose drugs all the time.
Meanwhile in Holby, a man, Sean, who's just been released from prison goes home to change, avoiding his mother, and leaves home with some money. His mother Kim returns home to find only a message from him and is soon interrupted by one of Sean's acquaintances, Jay, who's demanding to see him but she explains that he's not there.
Back at the ED, Hanssen speaks to Elle outside the ED and explains the situation regarding the press and the drugs. He also tells her that the build up of events including Jacob being shot and Lofty accidentally killing an agency nurse has led to the trust becoming involved. He explains to her that they'll want someone to be made responsible and hints that that person would be Connie. Elle tells him she'll do what she can to help.
Meanwhile Gary and Chloe, a father and daughter, leave for a day out together but before they go Chloe's mum Rebecca does a breath test for alcohol on Gary. They park up eventually and Chloe tells him that her and her mum are moving abroad. Shortly after, Chloe discovers a bottle of vodka in the glove compartment and gets out the car angrily. However, Kim is also driving along in search of Sean and she ends up hitting Chloe when she steps out into the road unexpectedly. She accompanies them to the ED.
Elsewhere, Sean is in a café in a shopping centre when Jay walks in to find him. Sean claims that he did his time but Jay is still looking for revenge for what he went to prison for. A fight ensues and they end up both falling through the glass window at the front. Matters are only worsened when a hanging pane of glass falls and impales Jay in the back, whilst Sean takes the opportunity to escape.
Rita sees Iain for the first time at work and ignores him after she saw him with another woman the previous week. Robyn and David are preparing their first meeting of the mortality café and he reveals a cake he's baked for it. Max continues to struggle in Zoe's absence but Dylan attempts to provide him with some support. Jay is admitted to the ED, and Sean follows soon after.
Elle notices Louise putting away some drugs stock and inquires about tramadol being a control drug, but Louise tells her that it was Charlie who put it on the register. She decides to speak to him herself and Charlie tells her that everything's already been resolved and the investigation into the missing stock over, which makes Elle suspicious. Elle begins to treat Sean whilst Connie treats Jay. Also, Robyn is bumped into by Glen Thomas, a man exiting a lift in the ED, and he takes one of her flyers for the mortality café that she dropped on the ground.
Meanwhile Cal encourages Ethan to flirt with a patient, Jorgie, whom he recognises as the woman who works in the local delicatessen. He goes over and makes a fool of himself much to Cal's despair but before long, she drags him into the storage cupboard and begins kissing him. Meanwhile Dylan treats Chloe and it transpires that her injuries are minor as she was just hit by the side of the car, and she's got a fractured wrist. Rebecca soon turns up and blames Gary for Chloe's injuries, claiming he failed to look after her.
In the staff room, Charlie is speaking to Elle but is interrupted when he's needed outside. Elle notices that he's left his key inside his locker and looks inside to see if her suspicions are correct and she's surprised and shocked to find the pills inside and she pockets them. Meanwhile, just as Ethan is asking Jorgie to stop she collapses and Ethan's forced to call Cal for help. He arrives and it transpires that she was simply trying to use Ethan to get pregnant as her husband didn't want kids.
Outside, Big Mac finds Gary angry in his car. He tells Big Mac to have some of his vodka but it's soon revealed to be water in a vodka bottle much to his surprise. Sean later goes to the toilets but almost collapses outside when he's confronted by Jay and is re-admitted. Meanwhile, Elle takes the drugs to Rita and tells her she found them in Charlie's locker. Rita and Elle go to inform Connie of the incident. Elle asks whether they should tell Hanssen, but Connie tells her to leave it with her. She also tells Elle to not look in people's lockers, but Elle warns Connie that there's a price to pay and that amplifications could be had on both the ED and people in it. Connie dismisses her claims and tells her to leave, unaware that Hanssen had warned her of exactly this earlier that day, and that Elle was in fact trying to help her.
Lily treats Sean and realises he has some cracked ribs and decides to send him for some chest physio. Connie interrupts and asks who's patient he is, and Lily reveals that Elle was treating him, leaving Connie angry that she abandoned her patient. She confronts Elle outside the ED and informs her to do her job. Elle responds by telling Connie she's on her side and that she knows what's best for the ED but Connie dismisses this due to the short duration of her time there.
Outside, Gary has set up a makeshift bowling alley along the paved area outside the ED and Big Mac brings Rebecca and Chloe to see. Upon arriving there, they enjoy it as a family as Rebecca finally sees that Gary is a good dad after all. As night falls, Elle sees Hanssen exiting the ED ready to leave and assumes that he's been told about Charlie. She starts to discuss it but soon realises that he doesn't know, and he responds shocked to what he heard as she dropped Charlie's name into the conversation.
Meanwhile Jay goes to see Sean and demands an apology as Sean was responsible for his father's death, although it was an accident. Sean tells him that he's had his punishment of five years in prison but eventually apologises anyway to keep Jay happy. After Jay leaves, Kim goes in and they reconcile.
As news of the pills being in Charlie's locker has reached Hanssen, Connie and Rita are forced to question him. Charlie explains that there's a reason behind it but he can't say as he made a promise. Given no other choices, Rita is forced to ask Charlie to go off duty with immediate effect. Charlie leaves and is questioned on the way out by various staff members and Connie explains that Rita has been given no option but to put him on leave. After Charlie's left and they're all crowded at the ED entrance, Jacob asks Connie for more of an explanation for Charlie leaving and Connie replies that his "little friend" decided to have a witch-hunt against Charlie, whilst pointing to Elle.
Robyn and David's mortality café is a success with people flooding into the pub. However, the cake that David made which was being saved for the raffle is started by a woman, much to his annoyance. Robyn also reunites with Glen who decides to turn up, and he tells Robyn that he was at the hospital to sort some things out following the death of his wife six months ago. They hit it off and exchange phone numbers, although this leaves David slightly disheartened. Rita goes back to her car to drive home to find that all her tyres have been slashed. She goes running to Iain for support and he offers to make sure she gets home safely.
Elle exits the staff room and is met with bad reception from the rest of the staff who've heard about her getting Charlie in trouble. She goes to Jacob, thinking he'll still be okay with her, but he too tells her she got the wrong person and walks away angry. Meanwhile, Big Mac is in the bathroom in the ED, clearly shocked by the events of the day, knowing that he's really responsible.
The episode was an hour long, 10 minutes longer than a regular episode. This was due to the fact 10 minutes of extra material was written by Sarah Beeson and directed by Steve Hughes. This 10 minutes, which was spread across the episode, featured only Cal and Ethan from the main cast. Although the scenes were canon, they didn't link in with the rest of the episode. Cal and Ethan's appearance in the episode was uncredited.
Reviewing for the Radio Times, Alison Granham commented on Elle's role in the episode saying "New consultant Elle Gardner is a fifth columnist, a management lackey and a snoop, a puppet of austere hospital boss Henrik Hanssen. He wants someone on the inside of an emergency department in chaos that’s had its fair share of run-of-the mill NHS problems: 'A staff nurse being shot… a nurse killing another nurse.' Blimey, has anyone called Jeremy Hunt?"
She also commented on the additional storylines shown in the episode including Cal and Ethan, which she said that viewers should "prepare to howl into a cushion during another one of those excruciating Ethan-coaches-Cal-in-the-ways-of-love stories".