A new midwife, Chummy Browne, arrives at Nonnatus House, and finds it difficult to prove herself. Meanwhile, Jenny befriends a young Irish prostitute who is expecting a baby, and is shocked by the Church's treatment of the girl.

A new baby is snatched from her pram, sparking an area wide search. Jenny is more familiar with the kidnapper than she realizes, Cynthia blames herself when a patient becomes gravely ill, and Chummy's romance continues.