Tom discovers that the family is throwing Lewis a childish birthday party in honor of his 21st birthday so he convinces Chris to treat the birthday boy to a night of guys-only partying. Meanwhile, Susan finds out that her new job as a restaurant hostess may cause her to miss her brother's birthday entirely.
Tom notices that his new doctor, Jim Coglan, has an old portrait of Susan up in his office and discovers that the man was actually a childhood friend of Susan's who used to hang out on a tree outside of her window. Meanwhile, Bill tries to get his old lucky sweater back from Lewis who seems to have fallen in love with it.
Tom wants to turn a storage room into his own private sanctuary so he hires a contractor named Mike after meeting the man's parents, who are good friends of the Kellys, only to learn that his work is suffering due to his failed marriage. Meanwhile, Mary is feeling guilty because she never told Chris that she dated Mike in high school.
Tom tries to convince Chris that the family is taking advantage of his overly-helpful generousity and decides to loosen him up by taking him golfing. Eventually Tom's plan to make his brother-in-law less helpful and more laidback backfires when the family starts to rely on Tom to takeover all of Chris' chores.
Tom and Susan, newly transplanted to Kansas City, are invited over for dinner and game night. The reserved Tom, terrified at the prospect of being thrown in feet first with such a tight-knit group of people, begs Susan to decline the invitation. But, of course, she accepts and soon Tom finds himself thrust into the close-knit Kelly clan – complete with game-playing, dinner-song-singing and collective corn-shucking, and initiated into the dreaded "doghouse system."