When Poirot is having dinner at a restaurant the waitress draws his attention to a old man, an artist with a strict routine.
He eats there on a certain day and has a particular set of dishes but recently he has varied the days he attends and the menu which piques Poirot's little grey cells.
The old artist is soon found dead from a fall, he was an eccentric who did not allow his paintings to be sold. Now he is dead, the paintings are valuable.
Suspicion falls on his twin brother, they both fell out some years earlier over a woman and not spoken since then but he too also dies after suffering a long period of ill health.
As Poirot states, there is a significant lack of suspects in this matter so the suspect is rather obvious. What we do get is Hastings being interested in the cricket score which is a running theme in this episode. The director also pays great attention to period detail with money spent on art production and extras such as the pier scenes.