Martin kidnaps Flo and Junior by pretending to take them on a family outing, leaving a ransom note for Ben. Flo sees this as a chance to get rid of Junior. Martin escapes from prison and arrives at the house, with Junior asserting Martin is his uncle. However, Ben leaves his keys in the car, and Junior drives through Big Ben's sporting goods store, leading to Ben's individual retirement account being seized to pay for damages. However, hearing that Junior was returned 30 times, Ben decides to love him. Finally, Junior wins a Little League game by belting rival players with a bat for bullying him. Ben gives Junior his lucky prune, which his grandfather gave him shortly before he died, and which he considered a special bond.

He then sabotages Lucy Henderson's 6th birthday party, after she snobbily bans him from her magic show for touching her presents. Next, Junior ruins a camping trip with the neighbors by urinating on the campfire, and luring in a bear to scare Roy's kids. Junior's bedroom catches fire when he shorts out the clown lights, and Big Ben calls him 'The Devil.' Junior throws Flo's cat at Big Ben and they both fall down the stairs and are injured. Shortly after Ben and Flo bring Junior home, Big Ben visits them, and is shocked that they adopted. The film is interspersed with scenes of an imprisoned Martin looking to escape and meet Junior. He often causes chaos, and is pen pals with serial killer Martin Beck, the 'Bow Tie Killer'. However, he is a devilish and incorrigible child.

Wanting a child, Ben seeks help from adoption agent Igor Peabody, who presents him and Flo with a cute 7-year-old boy named Junior. Meanwhile, Ben and his wife, Flo, cannot conceive, and visit a fertility doctor who states they are both infertile. Although Ben has worked for his father for ten years with nothing in return, his father plans on selling the company to the Japanese rather than giving it to his son, considering his son 'too nice' to be his heir.

Ben Healy is a kind man working for his father, 'Big Ben' Healy, a successful, but tyrannical sporting goods dealer running for mayor.

Problem child bow tie killer