Nonnatus House prepares for the annual summer fête, but when a baby show is announced, the girls must find a host for the proceedings. Meanwhile, a patient of Jenny's puts her life at risk, and Sister Bernadette remains troubled.

Doctor Turner is concerned by the spread of tuberculosis in the community, Jenny tries to repair a father and daughter's fractured relationship, and Sister Bernadette receives devastating news.

The nuns and midwives are busy preparing for Sister Evangelina's surprise jubilee celebrations, marking 50 years since she took her vows, but a face from the past threatens to ruin the party for the guest of honour. It's back to business when a young woman with Down's syndrome is brought in feeling unwell. To everyone's surprise, they discover she is six months pregnant, causing some of them to think the worst, and the staff are joined by new nurse Patsy, whose sense of humour and no-nonsense attitude make her an instant hit.

Tom, the local curate, asks Trixie to join him for a day of cricket. She accepts, but the date is disastrous. Shelagh decides to talk to Dr. Turner about adopting a baby. Patsy, struggling to adapt to the unpredictable and chaotic life that midwifery brings, upsets a young mother in the clinic.