Buck Russell is not the most reliable and trustworthy person around, and when Cindy Russell (his sister in law) and Bob Russell (his brother) use him as a last resort to babysit their children Miles, Maizy and Tia (who is a rebellious 16-year-old), Buck agrees to fill in while Cindy and Bob go to Indianapolis to visit Cindy’s ill father. While over at the house, Buck does his usual routines including going to smoky bowling alleys and smoking cigars. Yet, the longer and longer he is around with Miles and Maizy and the more he witnesses Tia slowly get seduced by her boyfriend Bug, Buck learns responsibility and more to life than just being an eligible bachelor and having fun.
Bob Russell (Brown), his wife Cindy (Bromka), and their three kids, Tia (Kelly), Miles (Culkin), and Maizy (Hoffmann) have recently moved from Indianapolis to the Chicago suburbs because of Bob’s promotion. Tia resents her parents for the move. Late one night, Cindy and Bob receive a phone call from Indianapolis informing them that Cindy’s father has suffered a heart attack. The couple makes plans to leave Chicago immediately to be with him. After hearing the news, Tia accuses Cindy of abandoning her own father.
Bob suggests asking his brother Buck (Candy) to come watch the children, which Cindy objects to. While Bob and Cindy are upper middle class suburbanites, Buck is unemployed, lives in an apartment in Chicago, and earns his living by betting on rigged horse races. Buck’s girlfriend Chanice (Madigan), owns a car repair business. Since no one else is available to help them, Bob and Cindy have no choice but turn to Buck, who agrees to help.
Buck hits it off with Miles and Maizy, but Tia is suspicious, and the two engage in a battle of wills. When Buck meets Tia’s boyfriend, Bug (Underwood), he warns his niece that Bug is only interested in her for sex. Buck repeatedly thwarts her plans. Over the next several days, Buck deals with a number of situations, including taking the kids to his favorite bowling alley, making over-sized pancakes for Miles’ birthday, dealing with a drunk clown, and speaking with the school principal about Maizy.
When Buck threatens Bug with a hatchet, Tia makes Buck’s girlfriend think that he is cheating on her with their neighbor (Metcalf). Concerned after Tia sneaks away to a party, Buck decides to go looking for her rather than go to a horse race. Thinking that Bug is taking advantage of Tia in a bedroom at the party, he forces the door open, but walks in on Bug with another girl. Buck ties up Bug and throws him into the trunk of his car. After finding Tia, Buck lets Bug out of the trunk to apologize to Tia. When he is finally released, Bug takes back the apology and flees. Buck then begins striking him with golf balls. When Cindy and Bob return, Tia and Cindy resolve their issues. Buck then returns to Chicago along with Chanice.