The story opens in dramatic fashion, in the thick of an action-packed scene. The hero of the story, known only as the Commander, declares “We’re going through!” A near-hurricane force storm and freezing temperatures assail the huge Navy hydroplane that he commands. The Commander decisively rebukes his subordinate, Lieutenant Berg, for suggesting that they won’t make it. The Commander gives orders and does not ask for the opinions of lesser men. He barks commands as the rest of the crew looks on in admiration, fully confident that “the Old Man” will save the day, barreling full speed ahead. 

This action comes to an abrupt halt with the sharp words of Mrs. Mitty saying, “Not so fast!” The adventurous scene was only a daydream that Mitty has had while driving his wife into the town of Waterbury. The excitement of the fantasy causes Mitty to drive faster than his wife’s preferred 40 miles per hour. Mitty’s fantasy is so real to him that he seems not to recognize his own wife, who is “grossly unfamiliar.” After driving on in silence, Mrs. Mitty notes that Mitty seems tense. She says that it must be “one of [his] days,” suggesting that Mitty often suffers these spells. She expresses her desire that Mitty should go to their doctor, Dr. Renshaw, for a checkup.

As Mitty drops his wife off for her hair appointment, Mrs. Mitty reminds him to buy a pair of overshoes. Mitty does not think he needs them, but she insists. This appears to be a recurring argument since she says that they have “been through all that.” As evidence that Mitty needs overshoes, Mrs. Mitty declares that he is no longer a young man. This statement causes Mitty to rev the car’s engine, a minor act of rebellion. Paying no attention, Mrs. Mitty remarks that Mitty is not wearing his gloves. She asks if he has lost them. Mitty retrieves the gloves from his pocket and puts them on. Once Mrs. Mitty is out of sight, he commits another small rebellious act by taking them off again. Stopping for a red traffic light, Mitty seems lost again in his thoughts until a police officer yells at him. Mitty has failed to notice that the light is now green. In response to the police officer’s authority, Mitty not only moves ahead, but he also puts his gloves back on.   

In search of a parking lot, Mitty drives past a hospital, which triggers another daydream. In this fantasy, Mitty plays a world-famous doctor. The millionaire banker Wellington McMillan awaits in the operating room. A pretty nurse informs Mitty that Drs. Renshaw and Benbow have been assigned the case, and that two specialists have flown in to assist. However, the four doctors together appear unsure how to save McMillan. As they explain the dire situation to Mitty, a “huge, complicated machine” begins to make noises, indicating that it is about to fail. Mitty shows his superior intellect and unorthodox thinking by demanding a fountain pen. He inserts the pen in place of a faulty piston but warns that the fix is not likely to hold long—certainly not enough time for the four doctors to operate successfully. Deferring to Mitty’s superior skill and knowledge, Dr. Renshaw begs Mitty to take control of the operation, which he does.