A outbreak of typhoid erupts, and suspicion over who the carrier could be threatens to break apart a closely knit family. Sister Winfred faces a personal dilemma when a local teacher is revealed to be pregnant by a married man. When the woman takes matters into her own hands, Sister Winifred is forced to consider the role her own prejudices may have played. Meanwhile, Barbara inadvertently agrees to go to dinner with Tom, but is wracked with worry about how Trixie will react.

Sister Julienne is seconded to a maternity ward, and is impressed by how modern technology is being used to help the mothers - but is left with a moral dilemma after assisting on a traumatic birth. A young man from Poplar is delighted to be accepted into university, but his mother is less than happy. His dreams are jeopardised when his girlfriend gets pregnant, a development that puts pressure on the whole family.

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.