New postulant Sister Catherine arrives at Nonnatus House. Disappointment strikes as responses for the measles vaccination clinic remain low. Dr. Turner suggests sterilization to a mother of seven if she no longer wants any more children.

It is the beginning of a new decade in Poplar. Set in 1970, chaos erupts as Isle of Dogs activists bid for independence. Amid the turmoil, the midwives work tirelessly to keep Nonnatus House running while addressing complex social and health challenges. 

Call the Midwife follows the nurses, midwives and nuns from Nonnatus House, who visit the expectant mothers of Poplar, providing the poorest women with the best possible care.