When Carries tells Doug to find a way to invest their tax return check, Doug decides to buy an ice cream truck he sees for sale. Thinking this is a good way to make money, he sets out to sell ice cream. Trouble comes when he tries delivering in another truck driver's zone, leading to a war of the ice cream men.
A woman keeps calling Doug's house, claiming to have spent a romantic weekend with him, but Doug has no idea who she is and tries to find a way to stop her from calling. Realizing that she is calling the wrong Doug Heffernan and leaving sexy messages, he sets out to stop Carrie from finding out, but when she does find out and does not care, Doug becomes even more upset about the situation.
When O'Boyle goes into rehab he asks Doug and Deacon to fill in for him as supervisor. Doug initially turns it down and tells Deacon to go for it, but then decides he wants it so that he can prove to Carrie that he is not content being a driver for the rest of his life. Soon Doug realizes he is in over his head when everything starts going wrong at the office.
Doug is reading Major a bedtime story and changes the end to make it scarier. The story ends up traumatizing Major, causing Kelly and Deacon to have problems getting him to be babysat by Doug.
Arthur also realizes that he can make money by charging people to fill a seat in their car, allowing them ride in the carpool lane.
When Doug and Carrie are not invited to the block party, Doug shows up anyways and ends up adopting a dog to prove he is a good person. Doug finds out that a dog is a lot of work and tries to find a way to return it without looking bad, but before he can, Carrie tells him they have to keep the dog a little longer because their neighbor, Glenn, says he can get her a good deal on a massage chair.
Arthur also tries to help Danny break his addiction to gambling, but ends up getting hooked on it too.
Deacon's son draws a picture of Arthur with crooked teeth, which leads Arthur to try to convince his family that he should get braces. Doug uses this idea to try to improve Carrie, by having Deacon's son draw a picture of her flat-chested.
When Deacon and Kelly buy a vacation house on a lake Carrie convinces Doug that they were able to afford it because the two were so cheap and never pay for anything when they are together. Doug and Carrie go to the new home with Deacon and Kelly and decide to get back at them by making Deacon and Kelly pay for everything. Spence is also trying to find a new job and Arthur decides to give him advice on getting one.
Doug, in an effort to be more healthy decides to become a vegetarian, which angers Carrie when he decides to push his new beliefs on her.
Doug runs into an old friend at his high school reunion and they decide to play a prank on the principle to get revenge for an event of the past.
When an apartment in Manhattan becomes available to Doug and Carrie, Carrie sees it as a chance to live out her dream of living in the city, but Doug wants nothing to do with it. He brings it up to her in hopes of looking good, because he knows that it is impossible to live there because of Arthur. Arthur soon decides to marry a singer he loved for a long time and move out, causing Carrie to want to move.
Doug and Carrie decide to go visit their priest for some marriage counseling, and while there they run into some old friends who just had a baby. This causes them to consider a child.
Arthur's wedding day is here but he soon finds himself without a bride when Ava St. Clair leaves him for not being gay. Doug, still mad at Carrie for lying about the apartment in Manhattan, decides he is going to divorce Carrie, and shows up the wedding drunk.
After Doug informs Carrie of his plans to leave her, she decides she wants to go to China and adopt the child they were going to get without him. Doug also wants the baby, so they race to get to the airport so they can get the baby.