Judith Richards is seated alone in her father's library at midnight, when a man enters, rifles her father's safe, and is examining his loot when a steel blade darts thru the portières, pierces him and he falls dead to the floor. Judith meanwhile has remained undisturbed, for she is seated with her back to the intruder and she is, moreover, stone deaf. When she finally rises to leave the room, she discovers the crime, and recognizes the victim as the stepson of her uncle. Detective Ferguson comes to the conclusion that the murder must have been an inside job, and the members of the household come under suspicion. Ferguson was right in his theory, but it is not until much evidence against each has been untangled that it is discovered which one was guilty - Summary by Book review digest v17 1921