The defense, instead of proving John didn't commit the murder, endeavors to demonstrate that there is just as much if not more evidence against Lawrence Cavendish than there is against his brother, John. The prosecution also maintains that John Cavendish burned the will that Emily Inglethorp drew up after her argument with him. Raikes, a neighboring farmer's wife, and when Emily Inglethorp confronted him about it, he resolved to poison her and blame her husband, of whom he was jealous and covetous of his inheritance of Emily's fortune and Styles Court. The prosecution succinctly relates the narrative that John Cavendish was wrapped up in an extra-marital affair with Mrs. Witnesses are cross-examined brutally by the prosecutor and the defense. Hastings gives a comprehensive account of the trial. Hastings secures a job at the War Office in the city and so is able to keep abreast of the goings-on. The trial takes place in London, and Mary rents a house in Kensington where Poirot stays with them to continue his investigation. Poirot explains to Hastings that he, Poirot, must appear to be working for John and on behalf of the defense at all times while looking for the final 'missing link' in his chain that will ultimately lead him to be able to indict, without a doubt, the murderer of Emily Inglethorp. Hastings is surprised to hear this assessment, especially after Mary told him, a few months prior, that she planned to leave John and that she never loved him.

When Hastings points this out, Poirot remarks that Mary is 'of those women who show at their best in adversity' and also labels her as 'an unusually jealous woman' (180). Hastings reports that Mary Cavendish never once accepts John's guilt and is a tireless advocate on his behalf. Two months pass before John is tried for the murder of his stepmother, Emily Inglethorp.

The mysterious affair