In this perplexing case by Agatha Christie, Hercule Poirot finds himself investigating the apparent suicide of his own dentist just hours after an appointment. Unconvinced by the simple explanation, Poirot delves deeper, uncovering a complex conspiracy of blackmail, espionage, and financial intrigue hidden behind the veneer of respectable society. As the body count rises, Poirot must untangle a deadly web where everyone has something to hide, and the simple nursery rhyme holds the sinister key to the truth.