Ellery Queen is the name used by both the detective and pseudonym for the author pair of cousins, Danny and Lee from NY. Ellery Queen is perhaps one of the most famous names in detective fiction next only to Agatha Christie, and the Grand master of locked room murders himself(shame on you if you don't know who I'm referring to).
Enough stalling, lets get down the mystery. Cornelia Potts in the overtly dominating matriarch of the Potts family and the Potts business empire, which they founded on selling cheap shoes. Cornelia had six children, 3 from the first marriage and 3 from her second. Cornelia's children from her first marriage are far from normal, they are deranged and quirky, and her children from her second marriage are normal and even have a sharp business acumen. This sharp contrast has led her to sympathize with her older set of children resulting in her indulging them and letting them have their way in childish pursuits.
The oldest and most notorious out of all her children is Thurlow Potts, a short, stout middle aged man who spends his mother's fortune in defending the honor of his family because of imagined slights through lawsuits, which he loses one after another. Ellery Queen takes a great interest in this quirky family, at dinner one night Thurlow challenges his younger step brother to a duel to death, at another one of his imagined slights. The saner potts, their lawyer and Ellery try to talk Thurlow out of the duel but he is adamant. So Ellery comes up with a neat little trick to exchange real bullets in Thurlow's guns with fake ones, Ellery does the task himself. The next morning at dawn, the two step brothers step outside the Potts mansion for the duel, Thurlow fires and his step brother falls.