As Poplar prepares for Christmas, the nuns travel to the Mother House to elect a new mother superior.Sister Julienne is the obvious replacement, and must face this possibility as her future at Nonnatus House hangs in the balance. As they ready to leave, Sister Mildred, an indefatigable sister from their order, arrives unexpectedly with her hands full with four Chinese orphans on route to the Children's Home at the Mother House.Touched by the plight of the children at the Home, the Nonnatus family and two new nuns, Sister Hilda and Sister Frances come together to give them a Christmas Nativity that they will remember.Back in Poplar, Trixie returns from Portofino refreshed and with her troubles well and truly behind her, and Valerie leads the baby ballet Christmas performance.