A new girl arrives Nonnatus House and finds it hard to earn the respect of Sister Evangelina. Jenny sees an unfamiliar darker side of life following an encounter with a runaway.

Christmas is coming, and in Poplar the midwives of Nonnatus House are busier than ever. When an abandoned baby is discovered on the steps of the convent, the whole community rallies round to provide food and clothing, and to try and trace his mother. Meanwhile, Jenny Lee finds herself drawn into the mystery surrounding elderly local woman Mrs. Jenkins, while Chummy is determined to stage an unforgettable nativity play.

Chummy makes an important decision, Jenny reconnects with Jimmy, and Cynthia's conduct is called into question after the death of a baby she delivered.

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.

The convent comes under threat of demolition. Fred's pregnant daughter and her young son come and stay with him. Jenny is wooed by a new love interest. Chummy and PC Noakes prepare for the arrival of their baby.

After the closure of Nonnatus House, the nuns and midwives finally move into their new premises. Sister Winifred arrives from the Mother House. Jenny is worried about new mother Merle’s mental state and the welfare of her baby who isn't feeding properly. Dr Turner is worried that it could be something more serious.