"All I Want for Christmas Is You" is the 1018th episode of Casualty and the 14th episode of the 31st series. It was preceded by "Not in Holby Anymore" and followed by "Bah Humbug". The episode was directed by Matthew Evans and written by Rebecca Wojciechowski. The events of the episode take place on 23 December 2016.
Ethan is awoken by Cal and Alicia in the next room, whilst still burying his feelings for her. They discuss Ethan's online dating profile, and Alicia sends a message to Penny, a dentist from Holby who's been messaging Ethan. Elswhere in Holby, father and son Sean and Peter are at a local ice-skating rink but when Peter collapses, he's forced to call for help.
Connie is doing her best to look after Grace at home with Jacob's support. After Connie arrives at work, she's surprised to see Peter in the ED, whom she had previously treated on cardiothoracics. Sean expresses concern to Connie that Peter's mother Annie won't turn up, despite the fact Peter wanted to meet her before he died.
Cal and Alicia are enjoying their day off at the Christmas market, but disaster strikes when a young woman, Livvy, falls from her balcony into Cal's arms. Although he's able to break her fall, they're both taken into the ED. Livvy is treated, but shortly after Carly begins vomiting up blood and is rushed into resus. Connie interferes with the Christmas decorations in reception, claiming them to be an infection risk for Peter, who is waiting for a double lung and heart transplant. Annie turns up and speaks to Peter for the first time since the accident, where a house fire broke out severely scarring him. Annie heads for the exit before long, but an argument soon breaks out between her and Sean. Whilst intervening, Ethan ends up getting hit in the face by Sean.
In the staff room, Alicia patches up Ethan's nose whilst Cal reveals that Charlie's treated him for his injured wrist. Connie interferes and tells Ethan that he won't have to stay late that shift due to his facial injury and that Peter has gone into renal failure. Charlie and Duffy share a kiss in a cubicle where Jez catches sight of them.
Ethan meets Penny over the road for the Christmas party although they're the first ones to arrive. Dylan and Seb try their best to save Carly who's suspected to have a gastric ulcer caused by overuse of aspirin. Despite their efforts, they're unable to save her and Dylan tells Seb that it isn't his fault, and Seb hugs him in the staff room. Just as they do, Max takes a picture of Connie's sign on the staff room door, unknowingly also getting their hug in the frame.
Everyone else arrives at the Christmas party soon after including Annie. Ethan speaks to her and convinces her to go back to the hospital to be with Peter which she does. Archie and Lily share a good time at the party and she goes back with him midway through. Penny soon notices the way Ethan is looking at Alicia and leaves, although they shared a kiss. Seb turns up at Dylan's houseboat, miserable and drunk. When Dylan tries giving him some pep talk, Seb mistakes this for flirting and makes an ill-judged pass at him. Dylan is shocked and backs away, leaving Seb mortified as he runs off.
Back in resus, news reaches Sean and Connie that there's a double lung and heart available for Peter and they're all delighted that he's got a second chance. Back at the party, news of Robyn's pregnancy gets out and everyone is delighted. Charlie and Duffy are asked to leave as they are drunk, but not before they reveal their relationship to all of the staff. However, just after leaving Duffy's shocked to see Ryan standing in the street having flown over from New Zealand.
Connie tries to get Grace to feed herself in an attempt to get her to be more independent. Although Jacob attempts to cheer her up by buying chocolates, Connie dismisses his kind gesture claiming that they have no nutritional value. Back at the flat, Alicia and Ethan share a chat and he finally admits that he's in love with her.