Before the last echo of the shot had trailed down Riverside Drive, Ellery Queen realized that he had just witnessed a murder. Robert Potts lay shot through the heart. Not only had Ellery Queen been a witness, but also Inspector Richard Queen and Sergeant Velie. Yet not one of them knew who committed the murder. This is the story of the Old Woman (Cornelia Potts), who lived with all her children (six) in the incredible Potts "palace" on Riverside Drive -- on its front lawn a great, bronze Oxford complete with trailing bronze shoelaces. Over the household hovers a ruthless killer who fits his cold-blooded crimes into the pattern of a Mother Goose rhyme.