April 1968. Racial tensions cast a shadow over Poplar, Nancy’s eyes are opened when she supports a dying woman, and Nonnatus House welcomes a new sister.

Sister Veronica is shaken when a mother reveals a terrible truth about her marriage, whilst Shelagh cares for a baby with a life-threatening condition and Nancy harbours a secret.

The maternity home is thrown into chaos by an outbreak of gastroenteritis, and Nurse Crane fights to save her career. Meanwhile, Cyril encourages Reggie to seek help.

A pregnant mother with a chronic heart condition falls unwell, Nancy grows suspicious of a young father’s erratic behaviour, and Matthew prepares for a visit from his father.

Trixie supports an underage mother through a difficult time, Monica Joan welcomes an unusual guest to Nonnatus House, and Sister Veronica spearheads a new council initiative.

Poplar’s housing crisis deepens, bringing a sad case to the attention of the team, whilst a worrying disease outbreak directly impacts the residents of Nonnatus House.

Dr Turner experiences the biggest test of his career, while Trixie’s approaching nuptials cause stress levels to escalate. Sister Julienne hatches a plan to save Nonnatus House.