Sister Bernadette is discharged from hospital, while a heavily pregnant Chummy resumes her midwifery duties. Jenny meets a new love interest, Fred's pregnant daughter pays him a visit, and Nonnatus House itself is under threat.

Nonnatus House and the surrounding area is evacuated when an unexploded bomb is found nearby. Meanwhile, Shelagh has doubts about her wedding to Patrick, and Jenny and Trixie help a man who is suffering from shell shock.

Now dating surveyor Alec, Jenny joins the other midwives in their superior new base, along with latest recruit, Sister Winifred. Jenny is concerned for Merle and Billy, a young couple whose infant boys are permanently ill, causing them to doubt their parenting skills, whilst added is stress provided by the fact that Billy's brother died as a toddler. Surprisingly, Sister Monica Joan accidentally provides Dr. Turner with the solution to the children's complaints, thus saving them. Chummy, meanwhile, drums up support for the newly opened, but under-used ante-natal clinic, taking advantage of a royal visit to put it in the spotlight. The day is a success, and to add to it, Chummy helps an older woman with a difficult birth, resulting in Sister Julienne asking her to return to work.

Jenny is promoted to Acting Sister at the clinic, much to the chagrin of the more experienced Trixie. Meanwhile, Cynthia is taken in by the theories of a visiting doctor, and a troubled, desperate woman seeks help.

Sister Julienne and Trixie attend to the female inmates at Holloway Prison, where they meet a troubled young woman. Meanwhile, Jenny deals with a vain patient, Shelagh receives horrendous news, and the girls celebrate Chummy's birthday.

Sister Winifred treats a young Jewish woman whose mother is plagued by remembrances of the Holocaust. Meanwhile, Shelagh tries to find a new way to channel her energy, and Alec suffers a terrible accident.