Doc asks Marty to meet him that night at the Twin Pines Mall at 1:15 a.m.. Marty asks him where he's been all week. Marty's girlfriend Jennifer (Claudia Wells) is his classmate at high school where Marty is always in trouble for being friends with Doc. Marty's dad George is a big league loser. & puts up with all kinds of nonsense from his supervisor Biff who totally rides rod-shod over George. Marty's mum Lorraine behaves like a nun & doesn't allow Marty any kind of freedom with Jennifer. The town clock tower was stuck by lightning 30 yrs ago & has been shut ever since. Marty has brother Dave & sister Linda. Lorraine's brother Joey was in jail & is just being released. Lorraine also reveals how she met George. George was in a tree, & was hit by Lorraine's dad's car who brought him home when he fell. Lorraine asked George to prom out of sympathy & when George kissed him at the dance, she decided to marry him.
at 1 am Marty heads to twin pines mall to meet Doc who is with his modified Delorean car. Doc demonstrates that his car is a time machine, works on Plutonium & starts at 88 mph. Doc reveals that he got the Plutonium from Libyan terrorists who wanted a bomb, but Doc delivered a fake. Libyans attack & kill Doc. Marty hide in the car & accelerate to 88 mph & travel back in time to 1955 (the year Doc discovered the time machine formula). Marty realizes he has landed in the past & tries to find Doc. He finds young George being bullied by young Biff. George has a penchant for peeping & falls from a tree on to the path on an oncoming car. Marty pushes him & gets hit himself. The car owner takes Marty home. Marty wakes to young Lorraine looking seductively at Marty.
Marty finds Doc & shows him the car to prove that he is from future. Doc promises Marty to get him back to 1985. The car required 1.21 GW, & in absence of plutonium only a lightning bolt will work. MArty remembers that the clock tower was stuck by lightning in 1955 & tells Doc. Doc also tells Marty that his messing with events in 1955 can impact the future. Already Marty can see his brother disappear from his wallet family photo.
Discord