Sally, Kurt, and Chris, three older children who have returned to live at home post-college, end up taking care of their 15-year old sibling, Brooke, as their parents are always off on trips. They are, however grown up they may be, not immune to the bickering ways of siblings.
Chris spots Brooke's boyfriend, Scott, kissing another girl and tells Sally and Kurt, who then confront Scott and try to pry the truth out of him.
Brooke celebrates her newfound freedom by throwing a house party, but while Chris and Sally think it's best that Kurt not know, he ends up hearing about it anyway.
Brooke, Kurt, and Chris find themselves caught up in the prank war between two rival high schools on Homecoming eve.
Kurt, Chris, and Sally begin to suspect that Brooke has taken up smoking, but when the word gets out, the parents are called in Arizona and warn the kids they might have to come home to oversee things again.
Kurt hires Chris to work at the family store after nagging him about getting a job, only their infighting over Kurt's bossing style causes Chris to quit after the first day. Meanwhile, Sally realizes that Brooke is unable to spot her friend's obvious romantic attraction toward her.
Kurt brings his new girlfriend home for the first time, and Sally, Chris, and Brooke like her so much, they notice she bears an almost exact resemblance to their mother. Meanwhile, Kurt comes to understand why Chris is constantly unable to get a job.
When Chris's college friend, Michelle, comes for a visit, he gets a little jealous when she starts to flirt with Kurt. Meanwhile, Brooke and Sally are forced to bunk together in the same room.
Kurt begins to have suspicions about Sally's boss' intentions when she starts spending long hours with him, only to learn that he is gay and simply needs the help of a very good employee. Meanwhile, Brooke asks Chris for advice about infusing more talking into her relationship with an overly-amorous new boyfriend.
Chris becomes the family representative for Brooke's parent-teacher conference, but Kurt gets upset when charmer Chris manages to finagle his way into the teacher's pants, an action which has big consequences for Brooke when her classmates' perception of her turns negative.
A none-too-pleased Kurt steps in as big brother when Brooke starts dating the brother of his old high school rival. Meanwhile, Sally tries to smooth out Chris' rough edges by giving him a makeover.
Chris becomes a member of the football team at work, but when a player fails to make a game, Kurt acts as a replacement and ends up upstaging Chris. Meanwhile, Sally becomes entranced by Brooke's birthday gift, a doll that looks very similar to Brooke.
Brooke gets her learner's permit and Kurt offers to teach her how to drive, but when he gets sick and Chris must quickly take over, the two go out for an ill-advised spin in their father's car in which Brooke backs up over some parking lot spikes.
When childhood friend from next door Bobby Norris comes to town for a visit, Brooke, Chris, and Sally gush over what a successful music reporter he's become, but Kurt soon finds out the real truth when Bobby fails to come through on some coveted concert tickets.
Kurt, Chris, and Sally attempt to give Brooke a sixteenth birthday party, but after no one shows up, leaving Brooke to think she has no friends, Chris discovers that Kurt wrote the wrong date on the invitations.
Kurt's well-meaning intention to spend time with Brooke by coaching her softball team goes awry when she feels he's too tough on her. Meanwhile, Chris accidentally runs over Mrs Norris' foot with the car, and the two clash when he ends up having to push her around in a wheelchair.