Lord Peter Wimsey Mystery, #5
In Strong Poison, Lord Peter first meets Harriet Vane, an author of police fiction. The immediate problem is that she is on trial for her life, charged with murdering her former lover. If Lord Peter does not prove she is innocent, he will lose her before he even persuades her to accept his proposal of marriage. But all the clues point to Harriet as having given Philip Boyes the arsenic that killed him. Lord Peter comes to the rescue!