Sally, Kurt, and Chris are three perfect examples of ""The Boomerang Generation,"" which, as the name implies, refers to kids who grow up, leave home for college, and then come right back to the nest. For their younger sister, 15-year-old Brooke Franklin, the sociological phenomenon is a lifesaver since her parents are always away on vacation. Left to fend for themselves by their globetrotting parents, the four create an unusual surrogate family marked by the usual sibling rivalries and power plays. Somehow they manage to overcome the pettiness, however, in a uniquely genuine attempt to create a nuclear family in the absence of one.
When Chris sees Brooke's boyfriend, Scott, kissing another girl, he tells Kurt and Sally and they try to get Scott to confess.
Things quickly get out of control when Chris helps Brooke throw a party and invites the band ""Dropline"" to the house. Meanwhile, Sally tries to keep the bash a secret from Kurt by taking him with her on a double date.
The annual tradition of pranks between rival high schools continues on the eve of Homecoming as Brooke, Chris and Kurt get involved in an egg fight with Brooke's rival high school. Meanwhile, Sally spends her Friday night baking cupcakes for the Homecoming committee but receives help from a fellow volunteer (""American Idols'"" Justin Guarini).
When Kurt (Joseph Lawrence), Sally (Sasha Barrese) and Chris (Kyle Howard) suspect that Brooke (Margo Harshman) has been smoking cigarettes, the town gossip calls the kids' parents in Arizona, and they threaten to return home.
Kurt pressures Chris to find a job. So Kurt hires Chris to work with him at the family store, but they end up fighting and Chris quits after one day because he can't deal with Kurt's managerial style. Plus, Sally helps Brooke realize a friend has a crush on her.
Kurt falls for a bridesmaid at a wedding who resembles a lot like his mom and brings her (guest-star Kelsey Oldershaw) home. Meanwhile, Kurt finds out why Chris has difficulties getting a job for himself. Lastly, spends his inheritance on a backyard hot tub.
Chris becomes jealous when his visiting friend, Michelle, flirts with Kurt. Meanwhile, Sally and Brooke are forced to share a room.
Kurt assumes the worst when Sally starts spending long hours with her new boss (guest star Benjamin King).
When Brooke's English teacher, Miss. Carelli, (guest star Nicole Steinwedell) requests a parent-teacher conference, the family selects Chris to speak with her because of his ""charming"" nature. However, Kurt gets fed up when he learns that Chris ended up sleeping with Miss. Carelli, making the kids at school think that Brooke is a suck-up.
Kurt becomes an overprotective older brother when Brooke dates the brother of his high-school nemesis and tried to get her ex-boyfriend, Sean, back. Also, Chris appoints Sally to improve his image so he can get girls.
Chris joins his office football team, but when a player does not show up to the game, Kurt comes to the rescue, stealing Chris's limelight. Meanwhile, when Brooke receives a look-alike doll as a birthday gift, Sally becomes obsessed with it.
When Brooke gets her learner's permit, Kurt decides to play big brother and teach her how to drive. Later, when Kurt catches Sally's flu, Chris takes Brooke out in their father's El Dorado against Kurt's orders and accidentally runs over parking lot spikes.
Kurt is frustrated when Chris, Sally and Brooke fawn over their neighbor Bobby Norris (guest star Adrien Wenner), who claims to be a reporter for Rolling Stone. However, when Bobby can't deliver promised concert tickets to Brooke, Kurt steps in to save the day.
After finding out that their parents don't have anything planned for Brooke's sixteenth birthday, Kurt, Sally & Chris decide to throw a suprise party for her the day before her birthday. Kurt and Sally organise everything, leaving Chris to just get Brooke to the party. When Brooke arrives home from school distraught that she has no friends, Chris tells her about the party to cheer her up. But when they get to the party, the only ones there are Kurt & Sally. They then find out that the invitations had the date of Brooke's actual birthday on, and Chris revels in the fact that Kurt screwed up. They manage to throw a party together quickly, in the bar at O'Roukes by promising Sally a date with Mike. Mrs Norris then gives Brooke her present from her parents, a brand new car.
When Kurt feels that he does not spend enough time with Brooke, he decides to coach her softball team, but ends up being too tough on Brooke. Meanwhile, Chris accidentally hits Mrs. Norris with his car and has to wheel her wheelchair around for the week.
Kurt tries to land a business deal with a major company, but soon realizes the wealthy older woman (guest star Kate Walsh) who owns the business wants more than a business relationship when she plans a night alone with him. Meanwhile, Sally gets Brooke a job at her store so Brooke can save to buy a car.
Brooke gets the lead in the school play, which is a rendition of Grease. But, upon telling her siblings, they realise she can't sing, but don't want to tell her and Brooke walks in on them mocking her. Kurt refuses to let Brooke quit the play, but he refuses to try out for a major league baseball, until Brooke says she'll only stay on the play if he'll try out. Kurt tries out, then Sally suggests he coach Brooke on her singing and dancing. On the opening night of the play, Brooke is amazing... Whilst the male lead is just horrible, and Kurt finds out that he's being asked to train with the team in Arizona. Meanwhile, Chris looks after the pet dog of a girl he is trying to impress, despite being allergic to dogs.
Kurt is hanging out with Sally's ex, Kevin under the premise it's all right for him to do this because Kevin was his friend before he dated Sally, even though Sally is still not over him, and Brooke & Chris had advised him it was a bad idea because Kevin broke Sally's heart. Sally finds out that Kurt is still friends with Kevin when she goes round to Kevin's to collect some of her stuff & finds Kurt hiding in the bath. Kurt tries to stop Sally hating Kevin by getting them to talk to each other, and he unwittingly gets Sally back together with Kevin.