Edith Thompson and the Missing Will

The novel is based on a famous murder trial that happened much earlier in the 20th century. Edith Thompson and her lover were convicted of the murder of Edith's husband. Charles meets again with his father, who both admit to having real doubts that the actual murders aren't custody. On top of all this, remember that whole pesky will situation? Sophia later admits to Charles that she actually knew about this because her grandfather had told her some weeks earlier. So guess who has the strongest motive to have killed Aristide? That would be Charles's kind of sort of thing, I'd say.