The reader is thrust right into what might well be the climax of a more traditional story. That story is taking place aboard a naval hydroplane equipped with eight engines and facing what appears to be a life-and-death situation. That situation is made all the more precarious as a result of ice forming on the pilot’s window. The level of danger is causing anxiety among the crew, but not fear. Never fear. No crew of any hydroplane could ever be afraid when Commander Walter Mitty is at the helm.
Except that Water Mitty is no naval commander. And ta-pocketa-pocketa sound that the hydroplane’s eight engines are making is actually being produced by the car that Walter is driving through his small town with his ever-vigilant wife by his side. It is Walter's wife who drags him out of the fantasy that begins the story, when she exclaims that he is driving too fast. Perhaps Walter was starting to get excited by the fantasy world he was imagining, letting it take over his actions in the real world.
In that real world, things are a bit more humdrum: Water Mitty is driving his wife to her hairdresser. As she exits the car, she reminds him not to forget to buy overshoes and to wear his gloves while he’s driving. Walter leaves with the gloves on, but takes them off at the first stoplight only to guiltily put them back on when a cop pulls up alongside him and tells him to get moving. The light has turned green and Walter’s car is still sitting, idling.
As his leisurely and somewhat-aimless drive takes him past the hospital, he removes the gloves again—only this time they are surgeon’s gloves and he is a renowned doctor being consulted on the important case involving millionaire Wellington McMillan. After all, the esteemed Dr. Mitty is also the author of a landmark book on treating streptothricosis. A fancy modern machine connected to the operating table is making a ta-pocketa-pocketa sound, indicating a problem with anesthesia. Like some sort of Depression-era MacGyver, Walter Mitty proves he is not just a great surgeon and best-selling author, but also capable of fixing the latest in medical technology using nothing but a fountain pen.
This fantasy is brought to an end by the voice of a parking-lot attendant. Walter Mitty has experienced some problems with parking cars before and as a result, has a bit of chip on his shoulder. Letting the attendant safely park his car, Walter seeks out the nearest shoe store and buys those overshoes his wife reminded him about. As he exits the store, a newsie strides by shouting the latest updates on an infamous trial that has everyone’s attention. And like that, Walter Mitty is in a courtroom, on the witness stand, a fearless sharpshooter standing up to the blistering cross-examination of the District Attorney, who ends his attack on Mitty's character by calling him a “miserable cur.”
This time it is the insult that brings Walter out of reverie. The phrase "miserable cur" instantly reminds Walter that his wife also told him to get some dog biscuits, so he heads for the smaller A&P down the street, avoiding the larger A&P on the way. Realizing that his wife’s hair will soon be done, he heads back to wait for her in the hotel lobby where he casually glances over a copy of Liberty magazine with a cover story wondering if Germany can rule the world through superior air power.
Midway through his fantasy of piloting a World War I bomber on a successful mission to destroy an ammunition plant in Germany, Walter is interrupted by Mrs. Mitty, who shows up to complain about having to spend so much time trying to find him in the big hotel because he practically disappeared into the big cushiony chair before asking him why he didn’t just put the overshoes on while he was in the store and asking if he remembered to pick up the dog biscuits. Walter’s response to this onslaught is deceptively simple and profoundly complex. " 'I was thinking,' said Walter Mitty. 'Does it ever occur to you that I am sometimes thinking?' "
Mrs. Mitty’s response confirms beyond a doubt that the cycle of Walter’s fantasies will be continuing for a long time. “I’m going to take your temperature when I get you home.” On the way to the parking lot to pick up the car, Mrs. Mitty instructs Walter to wait while she makes a quick stop into the drug store. The final fantasy of Walter Mitty that the reader is invited to share begins with his lighting up a cigarette and pushing his back to the wall of the drugstore in an attempt to escape from the coming onslaught of a rainstorm. As he looks up from his cigarette, he proudly accepts his fate about to be delivered to him from the raised barrels of the firing squad standing opposite him.