Within a Wall — Agatha Christie

Previously published in the print anthology The Harlequin Tea Set and Other Stories.

Alan Everard, a successful modernist painter, is married to the beautiful society girl Isobel Loring, who eagerly promotes her husband's work. At one of her tea parties, to which she invites the London art critics, she unveils her husband's latest masterpiece -- a portrait of herself. But Alan realizes the picture is lifeless. However, a sketch he has done of his daughter's godmother, Jane Haworth, is full of life and honesty. Alan soon discovers that the real contribution Jane has made to his life is not just her artistic judgment.