The final three characters die in ways consistent with what Christie shows us of their respective personalities. Blore, who proves himself bold but blundering, dies because he is foolhardy enough to return to the house alone. Lombard, who harbors a deep-seated sense of women as a harmless sex, dies because he underestimates Vera’s capabilities—first by putting her in a position to steal his gun and then, when he lunges at her, by assuming that she won’t be capable of shooting him. Finally, Vera is haunted by guilt about Cyril Hamilton’s death. She remembers the events with a nearly hallucinogenic clarity, smelling seawater and seeing moonlight. Additionally, she is powerfully affected by the “Ten Little Indians” poem and has a horrified fascination with the hook hanging from the ceiling of her bedroom. All of these traits come together, exacerbating the enormous shock of being responsible for someone’s death. Unable to cope, Vera falls into a kind of trance and gives in to the fate that she believes she cannot escape.
This combination of guilt, stress, and the supernatural suggestiveness of the poem might not really be enough to drive someone to suicide. But, however believable we find this last scene, the novel clearly intends it to be a realistic picture of an individual undone by guilt over her own actions. And Then There Were None is a murder mystery in which none of the victims is innocent, and in which most of them are plagued by feelings of guilt and remorse. Vera’s suicide—which parallels Macarthur’s earlier decision to sit by the sea waiting to die—is thus a fitting end to a novel that revolves around the administration of justice. Vera knows that she is guilty, and so, with Wargrave having set the stage, she administers justice to herself.