It's 1958. 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 - a joyous celebration. However, the midwife's good cheer is short-lived when the next day she's assigned a new patient, Molly Brignall. 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 aboard a Swedish cargo ship looking after the captain's daughter, who is about to have her first baby.