The murder case falls into the hands of Inspector Richard Queen of the Homicide Squad and his mystery-writing son Ellery. A set of onyx bookends in the private apartments on the top of the store reveal not only bloodstains but grains of fingerprint powder and an unusual assortment of books. Also, an ashtray full of half-smoked cigarettes is an important clue. The suspects include the wealthy victim's family and friends, some employees of the store, and possible members of a drug ring.