It's Christmastime, and young Ellery Queen has been invited to spend the holidays at a house party. During the eleven nights before Christmas, a series of anonymous gifts begin to arrive, each with increasing menace. Ellery tries to discover their source and meaning but to no avail. Finally, on the twelfth night, things turn deadly. Unable to solve the murder, Ellery returns to it decades later when he happens upon his diary. Will he finally be able to deduce the identity of the killer?