Problem Child/Recap/1st Movie

The film opens with a woman leaving a bassinet on the porch of a fancy home; the baby, named Junior, promptly urinates on the woman who picks him up. From there, he is repeatedly discarded at various homes throughout many years by guardians who have grown tired of his destructive behavior—which includes throwing a rattle at the window, giving a cat soap to eat, using a vacuum cleaner to suck up the fish tank, and demolishing a mobile home with a bulldozer in retaliation for his favorite toys being stepped on—until he is eventually deposited at a Catholic orphanage, where he continues to wreak havoc on the strict nuns.

Ben Healy is a pleasant but brow-beaten husband working for his father, Big Ben, a tyrannical sporting goods dealer who is running for Mayor. Recently, he has discovered that his father intends to sell his store and the land to a Japanese company rather than leave it to him; when he asks why, Big Ben reveals that it is because his son "stubbornly refuses to follow [his] example" by adopting an honest work ethic instead of a ruthless drive to usurp. He would love to have a son, but his selfish, gold-digging wife, Flo, has been unable to conceive. He approaches less-than-scrupulous adoption agent Igor Peabody with his dilemma, and Igor presents them with a cute 7-year-old boy, Junior.

However, Junior is hardly a model child; apparently mean-spirited and incorrigible. He leaves a path of serious destruction in his wake, and is even pen pals with Martin Beck, a notorious serial killer called the Bow Tie Killer. He sets his room on fire by using a clown lamp and throws the family cat at Big Ben and he falls down the stairs. He messes up a camping trip with the neighbors by urinating in the campfire, and manipulating a practical joke played on the kids by their father, Roy, by luring a real black bear to the campground. He makes Ben believe a bear is attacking the campground when it is really Roy in a bear suit who gets hit with a frying pan. Hearing Junior laugh, Ben finds out the kid is responsible for making him hit Roy. Next day, at a birthday party, Lucy, the snobby birthday girl, and her friends are very cruel to him and ban him from the magic show. Seeing Junior upset, Ben gives him his most precious possession, a dried prune that belonged to his grandfather (he thought it resembled Roosevelt), telling him it signifies a bond between two people. However, Junior wants revenge and sneaks a lawn sprinkler in her room, cuts off another girl's braid with scissors, puts a frog in the punch bowl, replaces the piñata candy with pickles including the juice, throws all the presents in the pool, and replaces the birthday candles with firecrackers.

Finally, Junior displays his effective but unethical method for winning in a Little League game where he strikes rival players in the crotch with a baseball bat after they tease him. Ben is having serious doubts about Junior, and decides to take him back to the orphanage. However, upon hearing he was returned thirty times, he decides to keep and love him, something no one has ever done. However, Junior becomes upset that his parents were going to send him back and despite Ben stating that he will not, drives Flo's car into Big Ben's store, and Ben's bank account is wiped out to pay for the damage. He is on the verge of cracking until Martin (believing that Junior is the criminal J.R.) arrives at the house, posing as Junior's uncle, and decides to kidnap his faithful correspondent, along with Flo, for ransom.

While Ben first sees this as good riddance to the browbeating Flo and the trouble making Junior, he soon notices signs that Junior is not the monster he appeared. In his drawer is the prune carefully wrapped up and through a series of pictures he drew, Junior depicts Flo and Big Ben as deformed monsters with hostile surroundings, but Ben as a happy person in a pleasant background, revealing that he really did value him as a father figure all along. Realizing that Junior's behavior was simply a response to how he himself had been treated, and that it has simply been bad luck that he has dealt with too many cruel and selfish people at such a young age, Ben undertakes a rescue mission to retrieve Junior back from Martin.

He then confronts his father (who is preparing to make a TV appearance for his mayoral campaign) to loan him the ransom money. When he callously refuses, Ben activates the camera that puts Big Ben unknowingly on live TV, where he ends up revealing his true nature on the news. Afterward, Ben steals Roy's car and goes to rescue Junior.

Ben catches up with Martin and Junior at the circus. Junior is rescued after escaping from Martin through a trapeze act and calls Ben "Dad" for the first time. Martin drives away, but the Healys are now on his trail. After a collision, Flo (who was stuffed in a suitcase) is thrown into the air and lands in the back of a farm truck loaded with pigs. Martin is arrested, but while being led away, he grabs an officer's sidearm and fires at Junior, but Ben shields him and takes the shot. Thinking Ben is dead, Junior apologizes for all the bad things he did and tells him he will never be naughty again and he loves him. Ben wakes up and tells Junior he loves him, too, and realizes the bullet ricocheted off the good-luck prune he was holding in his pocket. Junior asks Ben if he really believed that he was going to stop misbehaving, but Ben tells Junior he wants him to be himself. Junior then removes his bow tie and throws it over the bridge, perhaps as a sign that he has changed his ways not to be like Martin, but be himself. Junior is then carried home by his new father. The film ends with Flo in the truck looking out from the suitcase, only to be met by the rump of a pig.

The title track to the film, performed by The Beach Boys, plays over the end credits.