There Was an Old Woman

Cornelia Potts is a wicked old witch of a woman with millions of dollars, a henpecked husband, and six miserable children. When, one by one, the inhabitants of the Potts household are visited by death, Cornelia watches with delight. During a visit, Ellery Queen finds himself supervising a duel between Thurlow Potts and his half brother Robert, so he makes sure the guns are loaded with blanks. But when one of the brothers really dies, Ellery realizes he's up against a very cunning murderer.