In 1957, newly qualified midwife Jenny Lee begins her career in London's East End. She quickly comes to grips with the fact that her home is not a private hospital as she expected but a convent.

Chummy, a new arrival, sets out to prove her worth at Nonnatus House, but her willingness to please rubs Sister Evangelina the wrong way. Jenny witnesses the darker side of life.

In order to extend her experience in community practice, Jenny is placed on the district nursing roster. During rounds, she forms a friendship with an old soldier. Elsewhere, a pregnant woman in her 40s is enrolled.

A recently delivered baby girl is snatched from her pram, bringing the local community together as they search for her. Elsewhere, Cynthia assists expectant parents David and Margaret, and Margaret develops eclampsia.

Jenny and the nuns provide care after Peggy's brother Frank is diagnosed with cancer. Meanwhile, Jenny gets to know the siblings better.

Police return Sister Monica to Nonnatus House after she's found wandering near the docks. After she recovers from pneumonia, she heads back out into the community and faces accusations of theft.