As Christmas approaches, Chummy and Trixie are organizing a concert. Meanwhile, Patsy takes a pair of pregnant girls to a mother-and-baby home which proves to be ill run, and Cynthia is conflicted about her future.

A new midwife arrives at Nonnatus House, and finds it hard to fit into her new role. Meanwhile, Chummy moves into the mother-and-baby home, Trixie helps a young boy in terrible need, and Sister Evangelina is in denial about her illness.

As Sister Evangelina prepares to go on sick leave, a new midwife arrives at Nonnatus House, and they immediately clash. Meanwhile, Sister Julienne encounters a face from the past, and Barbara feels under pressure.

As dysentery sweeps through the area Trixie takes on her first official duty since her engagement to vicar Tom by organizing the Rose of Poplar contest whilst Phyllis is concerned for sickly Dolores McEvoy, who is living in a filthy hostel apart from her husband but is too ashamed to give the address. When Phyllis locates the hostel she also finds the source of the dysentery. Meanwhile young father-to-be Tony Amos is the victim of police entrapment when he goes cruising in a men's toilet. Dr Turner speaks up for him when he is taken to court but, although prison is avoided, bigoted attitudes make life difficult for him and his wife and the nurses' opinions are divided.

Sister Winifred meets a young prostitute and begins a campaign to improve the lives of women like her, Trixie reconsiders her engagement when Tom is offered a post in Newcastle, and Sister Monica Joan is unexpectedly called into action.

Sister Mary Cynthia returns to Nonnatus House, Barbara has trouble communicating with a pregnant Sylheti woman, Shelagh helps Patrick with his exhausting workload, and Trixie struggles to cope with her pain.

Phyllis deals with a diabetic teenager who has fallen pregnant, Sister Mary Cynthia comes into contact with a group of Irish Travellers, and Patsy organizes a square dance to raise money for the Cubs' trip to Norfolk.

A pair of school friends are unexpectedly reunited in the delivery room, and a mix up results in complications for both. Meanwhile, Barbara helps a couple in need of assistance, and Patsy's secret relationship with Delia pains them both.

Trixie and Sister Mary Cynthia help a deaf-and-dumb woman, and Barbara has a baffling case. Meanwhile, Fred's daughter arrives from Birmingham and interferes with his and Violet's engagement, and Delia has a proposal for Patsy.