The film opens on a room full of clocks ticking, coffee brewing, toast burning, dog food cans being opened by machines and a news story about stolen plutonium just before Marty McFly plugs his guitar into a gigantic amplifier which he blows out. We learn that he is at his friend Doc's home. Doc calls Marty on the phone and asks him to meet him in a parking lot that night at 1:15am. Once there Marty learns that Doc has created a time machine built out of a DeLorean he customized and which has been powered with plutonium he stole from terrorists. Doc shows Marty that it actually works, and once the DeLorean returns Doc sets the date in the car to November 5, 1955--the date he invented time travel.
But just after this moment, the terrorists arrive and kill Doc. Marty is able to escape by using the DeLorean to travel back to 1955. When he's there he meets George, a teenager at the local high school who is bullied by another student named Biff. He also meets a young woman named Lorraine who has become smitten with him. We learn that George and Lorraine become Marty's parents, and if he doesn't stop Lorraine from hitting on him and convince her to be with George he will forever alter his future.
Marty seeks out the younger version of Doc, and this is where he discovered his actions can forever alter the future. He convinces Doc to help him get back to 1985 as he doesn't have enough plutonium to power the DeLorean. As the story progresses Marty must take on Biff and help George stand up for himself and keep Lorraine from falling in love with him. In his attempt to do so he begins to be erased. Lorraine invites Marty to the school dance and while there Biff forces himself on Lorraine and when George sees it he becomes enraged and knocks Biff out. He then takes Lorraine to the dance floor where they kiss for the first time and this restores the proper order of Marty's life.
After playing an inspired version Johnny B. Goode Marty meets Doc at the clock tower where he has created a way to channel lightning into the DeLorean as he knows that the clock towere is famously struck by lightning as Marty tells him so. They are able to get the DeLorean up to 88 miles per hour (the necessary speed for time travel) and get it powered by the lighting strike. Marty returns to 1985 where Biff is now a concierge auto valet and his father, George is a stand up confident man and his mother appears radiant and healthy as compared to before he traveled in time. Jennifer, Marty's girlfriend arrives and then Doc appears in an upgraded DeLorean, which is not able to hover, and tells them that they must travel to 2015 to save their future children. The trio then takes off for the future.
