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.

        

The Sisters and the midwives have moved into a new building and have welcomed a new colleague, Sister Winifred. They have considerably more space and Dr. Turner manages to find a hall where they will be able to hold clinics two afternoons per week. After few of their patients come to the clinic, Chummy takes a bold step. Not only does she create a number of recreational activities she writes to Princess Margaret asking for an official visit, which she accepts. Meanwhile, Jenny is helping Merle and Billy Vickers. Merle had given birth only a few months ago but the newborn is always sick and his older brother is often ill. Jenny and Dr. Turner conduct a number of tests but they are all inconclusive. As it drags on, the Merle loses all confidence in her abilities as a mother. Sister Monica Joan thinks she knows what is wrong and puts them on the right track.

        

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.

        

Everyone at Nonnatus House is extra busy while Jenny is away recovering from her loss at the Mother House. The situation is made worse when an exhausted Sister Julienne collapses and Dr. Turner orders two weeks of bed rest. Sheilagh agrees to help out on the administrative side and promptly hires a new midwife, Patsy Mount. Mrs. Harper arrives with her daughter Sally fearing the young girl, who has Down's Syndrome, is pregnant. The father is Jacob Milligan who has cerebral palsy and lives in the same group home as Sally. The two want to keep the baby. Meanwhile, the nuns and midwives are also preparing to celebrate Sister Evangelina's anniversary of taking her vows and entering the sisterhood. She's not at all pleased at the idea. News of the celebration spreads and her brother Vincent, a homeless alcoholic, returns.

        

Patsy's brusque manner sees her taken off midwifery duties and reassigned to district nursing, where a patient reminds her of her past. Meanwhile, Trixie deals with a couple whose relationship has separated them from their families.

        

Jenny returns and is seconded to the London Hospital, where she meets a fretting mother-to-be. Meanwhile, Chummy's mother visits, a patient of Cynthia's becomes mentally ill, and Tom's nervousness leads to trouble with Trixie.

        

Chummy struggles to cope with her mother's terminal illness, with her experience affecting Sister Monica Joan greatly. Meanwhile, Shelagh and Patrick receive encouraging news, and Jenny makes an important decision.