The Christmas special will star Miriam Margoyles as Sister Mildred, who arrives unexpectedly at Nonnatus House, her hands full with four Chinese orphans. Having fled China, the child refugees were found abandoned in Hong Kong and are being adopted in the U.K. as part of the World Refugee Project. With Christmas preparations in full flow and the midwives busy caring for the expectant mothers of Poplar, these unexpected visitors cause joy and chaos in equal measure. The special also sees Trixie return to Poplar in time to cover for the Sisters as they leave for the Mother House. The Order’s Mother Superior has taken ill, and a new spiritual leader needs to be elected. It soon becomes clear, much to Sister Julienne’s horror, that she is the favored candidate.