A mother's life is turned upside down when her husband is arrested for gross indecency with a man. After Nurse Crane meets a clearly malnourished pregnant woman, a home visit reveals that she has given a false address and seems to have disappeared. Trixie is delighted when Tom asks her to oversee an official church duty. At Nonnatus House, Sister Monica Joan deliberately undermines Fred's attempts to bring a rat infestation under control.