And Then There Were None is a classic locked room mystery. Ten people are stranded on an island, and one by one they're murdered. A few days later, the police arrive to find ten murder victims and no murderer. Some time later, the murderer's confession washes ashore as a message in a bottle, and it's truly ingenious. It also brings up the issues of culpability, revenge, and justice.
Each of the ten victims was responsible, in a way, for a death that was not classified as murder, and one person decided to dispense justice. The least culpable and/or most remorseful died quickly, while the guiltier, less remorseful killers spent days dealing with increasing paranoia. Was, however, the killer accurate in assessing guilt? Anthony Marsden, the first victim committed vehicular manslaughter - but was he reckless (a higher degree of guilt) or merely careless (as the murderer decided)? Vera Claythorn felt deeply guilty for her crime, and yet didn't show it and was therefore considered unremorseful by the killer. Emily Brent seemed almost proud that she indirectly caused the death of her pregnant out of wedlock maid but was deemed less guilty - was that because she was a step removed, or because dismissing her employee followed the social norms of the day? And was the murderer dispensing justice or a psychopath rationalizing revenge?