Themes are the fundamental and often universal ideas explored in a literary work.
Most murder mysteries examine justice—its violation, through the act of murder, and its restoration, through the work of a detective who solves the crime and ensures that the murderer pays for his or her deed. And Then There Were None examines justice, but it bends the formula by making the victims of murder people who committed murder themselves. Thus, the killings on Indian Island are arguably acts of justice. Judge Wargrave does the work of detective and murderer by picking out those who are guilty and punishing them.
Whether we accept the justice of the events on Indian Island depends on both whether we accept Wargrave’s belief that all the murder victims deserve their deaths and whether we accept that Wargrave has the moral authority to pronounce and carry out the sentences. At least some of the murders are unjust if we do not consider all of Wargrave’s victims murderers. Emily Brent, for example, did not actually kill her servant, Beatrice Taylor. Thus, one could argue that she deserves a lesser punishment for her sin.
Christie explores the line that divides those who act unjustly from those who seek to restore justice. She suggests that unjust behavior does not necessarily make someone bad and enforcing justice does not necessarily make someone good . Wargrave’s victims, although they have violated the rules of moral behavior in the past, are, for the most part, far more likable and decent human beings than Wargrave. Although Wargrave serves justice in a technical sense, he is a cruel and unsympathetic man, and likely insane.
By creating a story in which every character has committed a crime, Christie explores different human responses to the burden of a guilty conscience. Beginning with the first moments after the recorded voice reveals the guests’ crimes, each character takes a different approach to dealing with his or her guilt.
The characters who publicly and self-righteously deny their crimes are tormented by guilt in private. General Macarthur, for instance, brusquely dismisses the claim that he killed his wife’s lover. By the following day, however, guilt so overwhelms him that he resignedly waits to die. Dr. Armstrong is equally dismissive of the charges against him, but he soon starts dreaming about the woman who died on his operating table.
On the other hand, the people who own up to their crimes are less likely to feel pangs of guilt. Lombard willingly admits to leaving tribesmen to die in the African bush, insisting that he did it to save his own life and would willingly do it again. Tony Marston readily owns up to running down the two children, and he displays no sense of having done anything wrong. Neither of the two men gives a moment’s private thought to his crime.