Ordeal by Innocence is noted as one of Agatha Christies darkest works. with a strong focus on the psychology of innocence.
While serving a sentence for killing his foster mother – a crime he insisted he didn’t commit – Jacko Argyle dies in prison. Two years later, the man who could have supported Jacko’s alibi suddenly turns up, and the family must come to terms with the fact not only that suspicion falls upon each of them, but that one of them is the real murderer.
Christie’s focus in this novel is upon the psychology of innocence, as the family members struggle with their suspicions of one another.
Ultimately it is revealed that the murderer was indeed acting under the influence of Jacko Argyle, and that the failure of his (carefully planned) alibi was, in hindsight, an ironic stroke of fate.
Anyway this novel does shows the treatment of adopted children. Though the victim may have been a very doting mother to all the children, it is nevertheless not your own blood. You never know what type of parents they originally have. A person may not did the act of murder himself, however he can instigate another to do it.