As Trixie and Matthew’s wedding officially begins, a series of small and great disasters threaten to impede the day. A horrific car crash turns into a race against time. Sister Julienne hatches a plan to save Nonnatus House once and for all.

Preparations for Trixie and Matthew’s wedding are underway as a joyous occasion that brings the community together. Nancy visits a homeless family, and it is not long before their plight is brought to the attention of Nonnatus house.

One of the boys of Buckle’s paper shop becomes unwell. Sister Veronica spearheads a new council initiative to monitor the health of working children in the borough. Trixie is thrown into a challenging case involving an underage mother.

Nancy oversees a child born out of wedlock, but things take a very unexpected and shocking turn. Dr. Turner and Sister Veronica discuss a new contraception procedure: the Vasectomy. The Board of Health delivers some unwelcome news to Sister Julienne.

Nurse Crane is shocked when her fitness comes into question during a ventouse training course. Trixie cares for a Hindu mother and her newborn twins, but it’s not long before an emergency gastroenteritis outbreak is declared at the maternity home.

As she sets about helping a mother whose newborn baby is suffering from a clotting disorder, Nancy is harboring a secret of her own. Sister Veronica meets a newlywed on her rounds, and the case shocks the women of Nonnatus house.

Lucille struggles with her mental and emotional health; Sister Julienne is deeply concerned by an angry red rash on a patient’s breast and a referral is quickly made to St Cuthbert’s.

With Christmas approaching, the midwives move to their maternity clinic and are delighted when their first patient is a familiar face. Life in Poplar returns to normal after the tragic train crash, and everyone unites for a festive talent show.

Christmas 1966 promises to be memorable one. The Nonnatus House team are faced with their busiest Christmas Day ever as the Maternity Home is filled with expectant moms and challenging cases.

Everyone at Nonnatus House is looking forward to traditional celebrations with all the trimmings, but nothing goes quite to plan. Sister Monica Joan is rushed to the hospital, and Trixie is incensed to receive a subscription to a Marriage Bureau as a Christmas gift. Meanwhile, a surprise reunion for Shelagh involves her in a deeply moving birth, and the Circus arrives in Poplar, bringing new friendships, new experiences, and an exciting adventure for Nurse Crane.