The 2013 Christmas Special was aired between Series 2 and 3. It is the 16th episode overall.
Shelagh (formerly Sister Bernadette) is getting ready to marry Dr. Turner, but agonises over her decision to leave the Order and has been avoiding the Sisters as a result. Meanwhile Jenny attends to expectant mother Yvonne Bridges whose husband Alan suffers from severe shellshock from serving in Korea. The discovery of an unexploded bomb results in the evacuation of Nonnatus House and the surrounding area, and everyone takes refuge at the community centre.
As the day of the wedding draws near Shelagh begins to have doubts, but things suddenly take a very serious turn when she returns from an errand and finds Timothy lying on the sofa struggling to breathe. Shelagh rushes Timothy to hospital where he is diagnosed with polio and imprisoned in an iron lung. On learning of what has happened Dr. Turner rushes to his sons side. Feeling helpless, Shelagh goes to the community centre where she is comforted by Sister Julienne who tells Shelagh that she believes her marriage will take place if it is meant to. As a result of Timothy's illness the wedding is postponed.
Meanwhile Jenny and Trixie try to help Alan and Yvonne. Trixie is particularly affected by Alan's illness, recalling how her father suffered from shellshock which forced her to help her mother to look after him when she was a child. A bomb disposal expert is called in to defuse the bomb, but he accidently detonates it, though thankfully no one is hurt and the damage is not as great as feared, and Constable Noakes walks into the community centre to inform everyone that they're heading home. That does not turn out to be the case for the residents of Nonnatus House as Sisters Julienne and Evangelina return to find the building condemned, and Alec tells them the impact of the bomb has badly damaged the convents foundation making it unsafe, and leaving its residents homeless.
Jenny and Trixie help Alan and Yvonne home and allow Alan to be at his wife's side as she gives birth. Timothy pulls through his illness, but the polio has damaged his legs and forces him to wear braces. The residents of Nonnatus House are given alternative accommodation, Chummy and Peter soon find a new permanent home to move into, and Patrick and Shelagh's wedding finally goes ahead.
Final appearance of the original Nonnatus House.
A deleted scene from this episode reveals Jane has gone to nursing school.
Sister Evangelina: (After Nonnatus House is condemned) "Been a while since I've wanted Adolf Hitler's guts for garters. But I'd cheerfully dance on his grave today".
Sister Julienne: "Poplar was doing so well. Its recovering from the war. It was being rebuilt. There was so much hope. So much work for us to do".
Sister Evangelina: "There still is, always will be. He'll have a reason for all of this".
Sitting on the steps of the church the two nuns look up to the sky.
Mature Jenny: (Narrating) "We ate our turkey at separate tables that year. Our community was scattered, though not to the four winds. We were offered refuge, separately and together, in temporary lodgings across Poplar. Christmas turned to New Year, and New Year to early Spring, and it was Chummy who found her new home first. Whilst the rest of us hoped and resumed our work as best we could. And when Nonnatus House was demolished, we heard its dying fall only in the distance".