Boxing Day sees heavy snowfall covering the country and the adverse weather causes major disruption across Poplar as roads become blocked and pipes freeze meaning families have to queue outside for water from standpipes. Sister Julienne must inform a family about the death of their loved one and uncovers an uncomfortable truth, while Valerie helps an unmarried couple living in a caravan prepare for their baby, but unforeseen complications knock her confidence in her ability as a midwife.
The team reunite but all is not well when a change of management shakes up Nonnatus House.
An explosion at the docks brings heartache to the people of Poplar, whilst Sister Ursula continues to ruffle feathers with her unpopular decisions.
The government plans to close down small hospitals in favour of larger establishments. Dr Turner and Shelagh prepare for an inspection that will decide the fate of Nonnatus House - but the staff is shocked to find Sister Ursula has no intention of helping to save the maternity home. Barbara comes to the aid of a woman from the Chinese community who is struggling to get on with her mother-in-law, and whose baby is seriously ill.
A woman expecting her third child realises she cannot afford to care for her baby, so makes the painful decision to give it away to her wealthy but childless cousin. Shelagh befriends the woman in the next hospital bed and Dr Turner confides in Timothy about his worst fears. Sister Julienne looks for a new recruit to join the midwives, and the community prepares to celebrate the opening of a new park.
A distant cousin of Fred's who has Down's Syndrome is taken in by the Buckles following the death of his protective mother, but Violet struggles to cope and Shelagh is forced to make other arrangements for his care. A new recruit prepares for her first day at Nonnatus House, and Trixie comes to the aid of a pregnant woman who is in urgent need of dental treatment to avoid an infection. The nurses discover what has happened to Sister Mary Cynthia, a revelation that has distressing consequences for Sister Monica Joan.
While the world anxiously awaits the resolution of the Cuban Missile Crisis, Valerie treats a pregnant Somali woman who has undergone female genital circumcision. The Nonnatus Team arrange for her to go into hospital, but she responds by going into hiding, and the situation is complicated further when it emerges that the woman's younger sister will soon go through the same process. Sister Mary Cynthia's depression is treated with electro convulsive therapy for depression, which she hopes will restore her faith.
Dr Turner is reunited with a couple whose daughter was born without limbs, and takes them to a specialist unit where she can be fitted for prosthetics. However, while the experience helps the girl's mother to realise that she is not alone, it proves traumatic for the father, who blames his wife for his child's condition. Nurse Crane takes charge of Sister Winifred's driving lessons, and Trixie thinks Christopher is hiding something from her.
Sister Julienne oversees the opening of a family planning clinic at the local community centre, leading mother-of-three Wilma Goddens to start taking the contraceptive pill behind her husband's back. Barbara is distraught when she discovers that her father has accepted a missionary posting in New Guinea for the next three years so will not be able to officiate at her wedding, while Violet suffers terribly with hot flushes, Christopher asks Trixie to meet his daughter, and Delia's heartache may finally be over.