Strong Poison
Dorothy L. Sayers
 Mystery author Harriet Vane has been accused of the murder of her former lover, Phillip Boyes. Boyes was a novelist and essayist who wrote in support of atheism, anarchy, and free love. Professing to disapprove of marriage, he persuaded a reluctant Harriet to live with him against her principles and they led a Bohemian life in the London art community. A year later he proposed, and Harriet, outraged at being deceived into giving up her public honour, broke off the relationship. During the year that followed, Boyes suffered from repeated bouts of gastric illness, while Harriet had bought several poisons under assumed names to test a plot point of her novel then in progress. Having returned from a holiday in North Wales in better health, Boyes dined with his cousin, the solicitor Norman Urquhart, before going to Harriet's flat to discuss reconciliation. That night he was taken fatally ill, apparently with gastritis. He died four days later after an agonising period of suffering. Although it was assumed at first that Boyes died of natural causes, an indiscreet nurse and some of Boyes' friends insisted that foul play was involved. A post-mortem revealed that Boyes' death was due to acute arsenic poisoning. Apart from the evening meal with his cousin, where every item was shared by two or more people, the only opportunity for poison to have been administered appeared to be in a cup of coffee, offered by Harriet Vane. Harriet is tried, but the result is a "hung" jury, thanks in no small part to the presence of Wimsey's aide, Miss Climpson, on the jury. With fewer than ten of the jury agreeing on a verdict, the judge must order a fresh trial to be held. Wimsey visits Harriet in prison, declares his conviction of her innocence, and promises to catch the real murderer. In the course of the interview he also openly admits his intention of marrying her, an offer which she politely but firmly declines. Working against time before the new trial, Wimsey first explores the possibility that Boyes took his own life. Wimsey's friend, Detective Inspector Charles Parker, conclusively disproves this notion, but Wimsey has planted a spy, Miss Joan Murchison, in Urquhart’s office and discovers the real culprit is Urquhart. Suspecting Urquhart's story that he, not Boyes, is in line to inherit the considerable fortune of their senile great aunt, Wimsey sends Miss Climpson to get hold of the great-aunt’s will, which she does in a comic scene exposing the practices of fraudulent mediums. Not only does the will name Boyes as the principal heir, but in Urquhart's office, Miss Murchison finds evidence that, misusing his position as his own family's solicitor, Urquhart embezzled the majority of the great aunt's holdings and subsequently lost them on the stock market. Urquhart knew that if his great aunt died, he would be exposed. Boyes, however, was unaware that he was heir to the money. With him dead, Urquhart would inherit the estate and hence his fraud would not be revealed. Miss Murchison also discovers a packet of arsenic hidden in Urquhart's office. Wimsey has now established motive and means, but not opportunity. But after re-examining the details of Boyes' famous last dinner (and perusing A.E. Housman's A Shropshire Lad, in which the poet likens reading dark poems to King Mithridates' self-immunization against poisons), he realizes that Urquhart laced an omelette with arsenic and shared it with Boyes after having built up an immunity to the poison with small doses over a long period. Wimsey tricks Urquhart into an admission before witnesses. At her retrial the prosecution presents no case and Harriet is set free. Exhausted by her ordeal, she again rejects Wimsey’s proposal of marriage. It is also in this novel that Peter finally persuades Parker to propose to Peter's sister, Mary. Also the Honourable Freddy Arbuthnot, Wimsey's friend and contact for the stock market, in this book finds a long-delayed domestic bliss with Rachel, the daughter of Sir Reuben Levy who was murdered in Whose Body?.