November, 1970. The challenges of midwifery hit close to home when a mother and baby home is evacuated. Nancy’s wedding plans take a surprising turn, and Sister Catherine takes her first vows.

The midwives help a family with a history of drug addiction. Dr Turner and Shelagh take the final steps in May’s adoption, whilst Joyce faces the disciplinary board.

It's March 1970. The team support a pregnant teenage girl whose parents believe in an immaculate conception. Demonstrations cause havoc for the Nonnatus team, whilst Nancy’s relationship blossoms.

It’s April 1970. Rising rates of gonorrhoea in the district cause alarm, and Trixie cares for an unmarried first-time mother recently diagnosed with a mental health condition.

Rosalind requires all her skills as a midwife when a disabled baby is delivered at the maternity home, whilst a gas explosion in an old tenement building shocks the community.

The Sisters welcome new postulant, Sister Catherine, to Nonnatus House, whilst a bold intervention boosts numbers for the measles vaccination clinic.

A solo delivery puts Sister Julienne’s skills to the utmost test. The Nonnatus team oversee the care of a man living inside an iron lung, and Cyril returns from Jamaica.

Joyce faces a difficult situation when a mother suffers postnatal complications, a council strike leads to an outbreak of Weil’s disease, and Cyril’s life is turned upside down.