The origin of evil.

The beautiful young Laurel Hill asks Ellery Queen to investigate a series of unusual anonymous gifts that have been received by her father, Leander Hill, half of Hill and Priam, Wholesale Jewelers. Roger Priam is Leander's partner, who uses a wheelchair. The latest gift, a dead dog with a mysterious note in a silver casket around its neck, has caused Leander to have a heart attack and die. Now Roger Priam (and his sultry wife Delia, who attracts Ellery like a carnivorous plant) has started to receive unusual anonymous gifts as well. Delia's nudist son Crowe, who is Laurel's boyfriend, and a cast of servants, are also on the scene. The mysterious gifts include some poisoned tuna fish salad, a green alligator wallet, a burned book and a bundle of worthless stocks and bonds, all accompanied by cryptic and ominous notes, and it seems as though they date back to a mysterious and possibly violent incident in the past of both Hill and Priam that gets them started in the wholesale jewelry business. Ellery Queen works out the significance of the series of gifts and the link that connects the notes and arranges a dramatic surprise that traps the criminal -- although the true criminal is not known until the final moments of the book.