A 17 year old, Marty Mcfly, lives a lousy life. His dad, George, a nerdy scaredy cat, and his mom, Larraine, is an alchoholic, who met George through pity, when her dad hit George with a car.
Marty's brother is a fast food cook, and his sister isn't allowed to like boys. He loses at a guitar audition, and the car that he and his girlfriend were supposed to take into the mountains, was smashed up by his dad's bully, Biff. The only thing that he can do for fun, is hang out with the local scientist, Dr. Emmit Brown (Doc). Doc shows Marty a time machine that he built, using a DeLorean, and stolen plutonium from terrorists. The terrorists find doc, and kill him, but Marty escapes into 1955, the year his parents met. The Time Machine runs out of fuel, leaving him stranded. He follows his young dad (Who's a bullied high school nerd)to the place where he meets his mom. Marty saves his dad from getting hit, and gets hit himself. He wakes up in his young mom's room, and realizes that she's in love with him. He tracks down the young doc, and asks for his help. The doc says that only a bolt of lightning can power the machine, and they decide to use the lightning that will strike the town clock tower in 1 week. In the meantime, Marty struggles to get his parents to meet, and fall in love, so that he'll have a future to go back to. He repeatedly saves his mom from Biff, and she grows closer to him. He devises a plan to get his parents together. Marty asks his mom to the dance, where his parents kissed for the first time. He has to harrass his mother, and his George will see him in the car and tell him to get away from her, therefore proving to his mom that George is a loyal boyfriend. In the car, Marty sees that his mom drinks and smokes, and warns her about the effects of them. Biff pulls Marty out of the car, and attempts to force himself on Marty's mum. When George comes to the car, he finds himself face to face with Biff, the bully who keeps beating him up. George stands up for himself, and beats up Biff. He and Larraine go the dance, and kiss, while Marty plays some music for them to dance to. Marty leaves the dance, and he and the doc harness the lightning into the time machine, and Marty goes back to 1985. He finds that his dad is now a famous author, and is Biff's employer, no longer a nerd. His mom is sober, his brother is a businessman, and his sister is dating. The doc leaves for the future, but comes back to tell Marty and his girlfriend, Jeniffer, that they have to solve a problem with their kids. The three leave for the future, to find out what there problem is.