It's 1958 and, returning from a long day of duties, Nurse Jenny Lee finds the Nonnatus House community gathered to wish her a happy birthday, before she, Chummy, Trixie and Cynthia head off to the cinema - it's a joyous celebration. However, the midwife's good cheer is short-lived when the next day she is assigned a new patient, Molly Brignall. Involved in an abusive marriage, Molly's due date is imminent and Jenny worries about the harm that could come to Molly and her children. Meanwhile, Trixie and Sister Evangelina find themselves in highly unusual circumstances, aboard a Swedish cargo ship and looking after the captain's daughter - who is about to have her first baby.