Jack Butler is an engineer at an automobile manufacturing plant in Detroit, Michigan. He lives with his wife, Caroline, their two boys, Alex and Kenny, and their infant daughter, Megan. Jack has a decent life and a decent home in the suburbs.
However, Jack's job seems to be stressful for him; he and his coworkers, whom he carpools with in the morning, all talk about their lack of sleep from the night before. When they drive in one morning, they talk about rumors of layoffs at their plant. Their supervisor, known only as Jinx, tells them not to worry about losing their jobs. The rumors persist while Jack talks to the assembly line workers.
Jack is called into Jinx' office during the day and finds out that he and the two men he and Jinx carpool with are being laid off. Jinx tells them that they'll be asked to come back at an undetermined time in the future. The guys are not convinced.
At home, Jack talks with his wife about finding another job and also having some time off to do work on the house he'd been planning. When Caroline, a former advertising expert, tells him she'd put her resume out on the job market as well, Jack suddenly becomes competitive, challenging her to a wager where the first of them to get a job will win $100. Some time later, Caroline wins the bet and goes to work for a prominent advertising firm. Jack becomes a stay-at-home-father and takes care of the kids, the errands, and the house during the day.
Jacks first few weeks at home are mostly a disaster: he discovers that the vacuum cleaner has a mind of its own and rampages around the house, he's inept at operating the washer and dryer, three repair-people come in one day and the baby eats chili. Jack also has trouble at the supermarket and he misunderstands the procedure for dropping Alex off for school. He also draws too much attention from one of his wife's more attractive friends, Joan, who is divorced.
As Caroline's career takes off she becomes an employee prized by her boss, Ron Richardson. At her first staff meeting, Caroline looks over the firm's ideas for one of their flagship clients, Schooner Tuna and, though she is constructively critical, receives scornful remarks from the rest of the staff. Caroline realizes that they are overworked, stressed out and have little or no experience similar to her's with regard to food prices or shopping.
Months later, Jack has not been called back to his work at the auto factory and there are no other jobs available in his line of work or similar fields. Jack becomes increasingly depressed, wearing the same flannel shirt every day (without laundering it), he gains weight, lets his beard grow ungroomed and drinks beer while watching soap operas. His attention to his kids even wanes a bit which makes it more difficult for him to convince his younger son, Kenny, to give up the baby blanket he carries around for security. One day, while watching a soap opera, Jack daydreams that Joan stops by. He begins to talk about his strained relationship with Caroline; Joan takes off her raincoat and is dressed in sexy lingerie. While Jack kisses her, Caroline walks in and finds them. She pulls out a gun, affixes a silencer to it, and threatens Jack. A struggle ensues and Jack is shot. As he dies, Ron Richardson appears and walks off with Caroline and Jinx appears and says that the auto factory was going to call him back to work. Jack wakes up, cancels the weekly poker game with Joan and decides to clean up his act. He gets the kids to follow a morning routine to get them off to school on time; he exercises with Caroline's friends and loses the weight he'd put on, and he fixes up the house. At one point, we see him throwing his flannel shirt into the fireplace, a gesture meant to encourage Kenny to give up his security blanket. Kenny refuses and Jack has a man-to-man talk and convinces his son to give up the blanket.
At a party thrown by Richardson at his palatial mansion, Jack is egged on by Richardson himself to compete in a race involving toys and other obstacles meant for children. Before the race, Jack, a fair sportsman himself, is persuaded by Richardson's subordinates to throw the race because his wife works for their host. Not wanting to jeopardize his wife's career, Jack stumbles just short of the finish line, preserving Richardson's dignity.
Caroline's schedule keeps her away from home more frequently, which has an effect on Jack and the family. Caroline also develops a new strategy for Schooner Tuna; she meets with the company's CEO and tells him that the only way to sell more of his product is to lower the price in light of tougher economic times. The CEO goes almost immediately for Caroline's ideas, which also include filming a TV ad that will express the company's new policy, with an included appeal to consumers. Caroline is charged with going to Los Angeles to aid in shooting the new ad, which takes her out of town on Halloween. Richardson comes to their house to pick Caroline up in a limousine, but before she leaves, Jack talks to her about all the changes the family has experienced in her absence. Caroline still goes with Richardson.
A few nights later, while Caroline is still out of town, some of the girls invite Jack out for the evening, leaving one of them, Annette, behind to sit with the kids. As a prank, the women take Jack to a male stripper bar. When he comes home late, he tries to call Caroline in California. Unknown to him and to Caroline, Richardson has snuck into Caroline's hotel room with dinner and champagne to celebrate their Schooner Tuna success; Richardson answers the phone and Jack recognizes his voice. Richardson abruptly hangs up on him. Caroline confronts Richardson, who suggests she leave Jack. She refuses and orders him to leave, punching him in the face when he won't. At home, Jack becomes furious when the phone rings and throws it across the room. He also kicks the TV, shattering the screen.
Annette, witness to Jack's meltdown, leaves and tells Joan the next day. Joan takes it as a signal that Jack and Caroline are through and races to his house to talk to him. She stretches out in the bedroom while Jack cleans up in the bathroom. Caroline, returning early from California after her confrontation with Richardson, finds Joan in her bed. When Jack comes out of the bathroom, after a lengthy contemplation with himself about having an affair with Joan, he finds Caroline, who is angry about finding Joan in her bed. The two argue, Jack telling Caroline that he heard Richardson's voice on the phone when he called. Jack storms out of the room saying he has a house to run. Caroline follows him and the two begin to reconcile when both Jinx and Richardson arrive at the house, both wanting Jack and Caroline to return to their jobs. At one point, Jinx yells at Alex and Jack hits him in the face, knocking him to the floor. Caroline tries to tell Richardson that she's quit and Richardson offers her a better working contract. The couple negotiate new employment deals for themselves and agree to return. The story closes with everyone watching the TV ad Caroline helped create.