The Duke of Frome John Langton with his wife, their baby born after complications during childbirth, a domineering nanny, nursery maid and valet arrive at Montague Hall for Lady Felicias Yuletide ball. During the evening the baby is taken from his cot. Inspector Mallory suspects an inside job by the valet when his secret wife arrives while Brown is more interested in the birth of the baby at a home for unmarried mothers. Mrs McCarthy under pressure from the diocese to provide a Christmas service fit for a Duke receives unexpected help from a vagrant she finds in the confessional.