Paul is a new kid in town with a robot named "BB". He befriends Samantha and the three of them have a lot of good times together. That is, until Samantha's abusive father throws her down some stairs and kills her.
In a parking lot, a thief tries to steal from a Volkswagen van but a robot named BB (voiced by Charles Fleischer) stops him. BB lets go of the thief, who is dazed. Paul Conway (Matthew Laborteaux) and his mother Jeannie (Anne Twomey) return from shopping and drive away in the van. Paul is the owner of BB, which he built. They arrive at their new house in the town of Welling Proper the next day.
Paul soon become friends with newspaper delivery boy Tom Toomey (Michael Sharrett). Paul has a university scholarship due to his vast intelligence and interests in neurology and artificial intelligence. As they move in, BB's batteries run low. The robot, which occasionally shows signs of autonomy, plugs himself into an electrical socket to charge up. At the university, Paul, Jeannie, and BB meet Paul's professor, Dr. Johanson, who gives them a tour of Paul's new laboratory.
A few days later, Paul and BB are cleaning the yard. Paul meets his next-door neighbor, Samantha Pringle (Kristy Swanson). Paul notices some bruises on her arm but Samantha tries to hide them. Sam'sabusive, alcoholic father, Harry (Richard Marcus), soon comes outside and stares at her menacingly. Samantha is frightened and returns to her father. That night, Samantha visits Paul and Jeannie. Her father soon drags Samantha home and beats her.
Tom helps Paul teach BB to deliver newspapers. They stop at the house of reclusive harridan Elvira Parker (Anne Ramsey), who threatens the boys with a loaded shotgun and expresses dislike for BB. The three walk away. Tom reveals that his father is a security guard at the university hospital. Walking further, they encounter a motorcycle gang. The gang insults Tom and they push Paul into a garbage bin. BB grabs the gang leader's crotch. The gang rides away, with the leader vowing revenge.
Paul, Samantha, Tom, and BB develop a close friendship. One day, they play basketball in the neighborhood. BB accidentally tosses the ball onto Elvira's porch. She stomps out of her house and takes the ball, refusing to give it back. BB's eyes freeze on Elvira as if he will never forget the insult.
On Halloween night, Samantha comes over with a bloody nose and asks for ice. Paul and Jeannie believe that her father is abusing her. Samantha goes out with Paul, Tom, and BB. Tom decides to pull a prank on Elvira. BB unlocks her gate and Samantha rings her doorbell. Alarms go off and they hide in the shrubbery. Elvira finds BB standing near her porch and shoots the robot. Paul is devastated by the loss of his friend, while Tom blames himself for suggesting the stunt.
On Thanksgiving Day, Paul and Jeannie eat dinner with Samantha. Afterwards, Paul and Samantha share their first kiss. Samantha returns home late at night, outraging her father, who punches her in the face and pushes her down the stairs, causing her to be rushed to the hospital. Samantha is left brain-dead. Dr. Johanson tells Paul that she will be put on life support for 24 hours and then the plug will be pulled. Paul remembers how BB's microchip links artificial intelligence with the human brain, and runs to Tom's house. With an idea in mind, he asks him for his father's keys to the hospital to sneak into Samantha's room and bring her back to life when the plug is pulled. They get the keys, and enter the hospital as Tom deactivates hospital power from the basement, Dr. Johanson pulls the plug on Samantha. When the hospital goes dark, Paul enters Samantha's room and drags her to his lab. Paul's inserts the microchip into Samantha's brain and brandishes his remote control, attempting to activate Samantha. Samantha's foot moves, causing Tom to faint. Paul takes Samantha to the shed at his house and activates Samantha. She opens her eyes mechanically and starts to breathe, with her hands in the position of BB's pincers as Paul teaches her to sit up.
The police arrive at Samantha's home and inform Harry that her body has disappeared. In the middle of the night, Paul finds Samantha staring at the window, looking at her father. Paul deactivates her. The next morning, Paul awakens and sees that Samantha is gone. He searches for her in the street, but there is no sign of her. Samantha is at her house, avenging herself on her father. Harry finds the cellar door open and goes downstairs. Samantha yanks her father off his feet and drags him to the furnace. She kills him by snapping his neck. Paul finds her in the cellar and sees her father's head burning. Horrified, he hides the corpse in a pile of coal. He goes home with Samantha and locks her in his bedroom.
That night, Samantha breaks free again. This time, she avenges herself upon Elvira for shooting BB. Elvira calls the police, but they hang up on her. A basketball bounces ominously in her living room indicating that Samantha has broken in. Samantha, now developing super-strength, grabs the basketball and throws it at Elvira, causing her head to explode. Elvira's decapitated body rolls on the floor and runs in circles, spurting blood and gore until it bounces off the door and lays dead on the porch.
At Elvira's house, police discover Elvira's corpse and Harry's body. When Tom learns that Samantha is killing people, Paul promises things will change. Tom refuses to budge, and the two fight. Samantha jumps out a window and attacks Tom, believing that he has injured Paul. Paul and Jeannie save Tom, but Samantha runs away. As Paul runs after her, the leader of the biker gang confronts him. As a police car arrives, Samantha throws the biker into the car's windshield. As she runs off, she is confronted by police. She makes her way back to Paul's shed. Paul meets her there and tries to comfort her. He is amazed as he realizes that Samantha is becoming more human, even saying his name tenderly. The police arrive and point at Paul. Samantha yells Paul's name and the police shoot. The bullet hits Samantha, who was defending Paul. She dies in his arms.
Later, Paul visits Samantha in the morgue. A malevolent version of BB emerges from Samantha's head, grabbing Paul's neck. Samantha/BB says, "Paul. Come with me, Paul". Off-screen, Paul screams as Samantha/BB crushes his neck.
The credits end with BB's name being said over and over again.Source: Wikipedia