
He returns to her the shiny buckle that has fallen from her shoe.

Hercule Poirot leaves the office of his dentist, Morley, after an appointment, and notices the arrival of Mabelle Sainsbury Seale. (may contain spoilers - click on expand to read) Other Agatha Christie books and short stories also share this naming convention, such as Hickory Dickory Dock, A Pocket Full of Rye, and most famously And Then There Were None.

The book's UK title is derived from a well-known children's nursery rhyme of the same name, and the chapters each correspond to a line of that rhyme. Poirot suspects, however, that there is more to the case than at first appears, and soon events confirm his worst suspicions. When Hercule Poirot’s own dentist, Henry Morley, is found dead from a gunshot wound, the official verdict is that he has killed himself a verdict apparently supported when it appears that he has given one of his patients a fatal overdose of anaesthetic.
