Alice Armstrong is receiving electric shock treatment for memory loss after her accidental shooting her mother. Six weeks after her mother's death her father Sir Aaron is also found dead from a blow to the head, his hands tied. Suspicion falls on Jim Magnus, the chauffeur and a former petty crook and on Peter Royce, the secretary, who loves Alice and was sacked after telling Sir Aaron not to send her back to hospital. But a conversation with debt collector Eddie Monk informs Father Brown that the dead man owed huge sums of money and another confession suggests that Sir Aaron tied his own hands. With the death solved Alice then recollects that she was not responsible for her mother's slaying.