Spoiler warning! Lionel Lampson is a wealthy older gentleman who enjoys fine art and the company of the upper classes. One night he escorts a vulgar woman named Gladys Ponsonby home from a dinner party. Gladys, who is a little drunk, shows off a new portrait of herself that she had commissioned. She tells Lionel a secret - the artist, John Royden, paints all his subjects first in the nude, then in their underwear, and lastly in their clothes. He is shocked and correctly deduces that this is why all the wealthy women in town are rushing to have their portraits painted by him. Gladys then changes the subject and asks Lionel about his relationship with a young beauty named Janet de Pelagia. Lionel is embarrassed until Gladys relates that earlier that afternoon Janet had called him a "crashing bore". Lionel is outraged and forces Gladys to repeat the entire conversation. He is so upset to hear what Janet thinks about him that he swoons. The next day he wakes and vows revenge.
As the story ends, Lionel mentions that he might have eaten too much of it, as he isn't feeling too well right now. In fact, he says, "come to think of it, I really do feel rather ill all of a sudden."
(If you don't get it, [Janet] sent him poisoned caviare as her revenge.)