Solly Spaeth is a financier whose machinations with the "Ohippi Hydro-Electric Project" have left a number of people much less wealthy than once they were, including his business partner, Rhys Jardin. Jardin's beautiful daughter Valerie is involved with Spaeth's son Walter. Rhys is so impoverished, he has to sell up his personal property at auction, much to the dismay of his daughter and his long-time servant/valet/trainer, Pink. Walter asks Ellery Queen to sit in on the auction and buy every lot, which is how Ellery becomes involved when Solly Spaeth is found pierced by an ancient sword whose blade has been coated with molasses and cyanide. Suspicion falls on a number of people, including the Jardin household, Solly's son, lawyer and his mistress, the kooky Winni Moon, but Ellery works through alibis and motives and traces the crime back to the murderer. A sub-plot of the novel is that Ellery has been hired to work on a screenplay and has been completely idle for weeks because he can't get in to see studio head Jacques Butcher; Butcher plays a much more prominent role in the next novel, The Four of Hearts.