There are those who feel that Dorothy L. Sayers ruined her Lord Peter Wimsey series with the introduction of the character Harriet Vane. I am on the fence about this. On the one hand, I don’t really enjoy Peter’s sappiness as he courts and marries Harriet. On the other hand, I like Gaudy Night, the mystery that Harriet solves herself.
I also enjoyed Strong Poison, the novel in which Harriet is introduced. Harriet, a mystery writer, is accused of poisoning her ex-lover, Philip Boyes, with arsenic. In 1930, when the book was published, no one quite understands why Harriet broke off with Philip. Philip convinced her, against her principles, to live with him without marriage, stating that he did not believe in it. Then he turned around and asked her to marry him, which Harriet views as his having tried her out. Her resulting anger seems to be the police’s motive. Lord Peter doesn’t believe it for a moment. He thinks Harriet is innocent and wants to marry her himself. Luckily, there’s a hung jury, so Peter has a month to investigate.
At first, Peter can’t get anywhere, because he can find no motive. Yet he is struck by the precautions Philip’s host at dinner took when Philip was taken ill to preserve the food. Peter is even more struck by the precautions he took not to be left alone with Philip or give him medicine when he was ill. But this host, Mr. Urquhart, Boyes’s cousin, had no opportunity to administer the poison, and Harriet did. Moreover, Harriet purchased arsenic as research for her book.
About halfway through, this mystery becomes more a puzzle about motive and opportunity than the identity of the killer. It skillfully unwinds, however, and does not cheat by hiding information from the reader.