Behold, Here's Poison

Uncle Henry has a history of heart trouble and doesn't wake up one morning. No one, even his physician, is surprised. But dear Aunt Gertrude, listening to Intuition, suspects Foul Play and insists on an autopsy. Since Aunt Gertrude is a cross between a battleship and a Victorian bulldog, an autopsy she gets.

Surprise! Uncle Henry was, indeed, poisoned. The problem is that all of his relations have a motive. You see, Uncle Henry was not well liked at all; he took positive delight in thwarting his erstwhile relatives. They included two sisters, one sister-in-law, a niece, two nephews, and an attending physician who all had reason to hate him, and all benefited in one way or another from his unlamented passing.