Who is Walter with and what is he actually doing during the story "The Secret Life of Walter Mitty"?Full detail

Walter Mitty is with driving his wife doing various errands during the story. Because Walter is such a daydreamer, he imagines himself as the hero of various fantasies that are suggested by events that occur in his real life. For instance, when the story begins, Walter is driving his wife to a hair styling appointment but, as he drives, he images himself to be a commander of an airplane crew flying through a dangerous storm. This is Mitty's way of dealing with his dominating wife and dull life.