Marty: Mom, Mom, what are you saying? You're actually defending him!
Lorraine sits down and has another drink.
Lorraine: I had it coming. He's my husband, and he takes care of all of us. And he deserves our respect.
Marty: Respect! Your husband? How can he be your husband? How can you leave Dad for him?
Lorraine: Leave Dad? Marty, are you feeling OK?
Marty! No! no, I'm not feeling all right! I don't understand one damn thing that's going on around here and why nobody can give me a simple straight answer.
Marty sits down next to Lorraine.
Lorraine: Oh, they must have hit you on the head hard this time.
She runs her hand through her son's hair.
Marty: Mom, I just want to know one thing.
He holds her hand.
Marty: Where's my father? Where's George McFly?
Lorraine: Marty! George, your father is in the same place he's been for the past 12 years. (takes a sip) Oak Park Cemetery.
Marty faces the camera with a horrified look on his face. Cut to Marty running through the cemetery. In the background is a factory. Marty finally finds a gravestone. It reads "In Loving Memory Of George Douglas McFly, Born April 1st 1938, Died March 15th 1973."
Marty: NO! No!
Marty kneels down in front of the gravestone. He pushes away some plants on the stone (maybe flowers?)
Marty: This can't be happening! (reads) March 15th 1973? No, oh please God no, no, please God, please God, no, this can't be happening! This can't be happening! This can't be.....
A shadow appears on the gravestone. Marty hears a twig snap and turns around. It's DOC and EINSTEIN!
Doc: I'm afraid it is happening Marty, all of it!
Marty: Doc!
Doc: When I learnt about your father, I figured you'd come here.
Marty: Then you know what happened to him? You know what happened, March 15th 1973?
Doc: Yes Marty, I know.
Cut to Doc's garage. It's a mess. Doc opens a book - Hill Valley Telegraph Archives March 1st - April 30th 1973. On the page he turns to is a headline - "George McFly Murdered: Local Author Shot Dead." We stay focused on the paper as Doc speaks.
Doc: (v.o) I went to the public library to try and make sense out of all the madness. The place was boarded up, shut down, so I broke in and borrowed some newspapers.
The camera turns to Marty and Doc.
Marty: I don't get it Doc, I mean how can this be happening? It's like we're in hell or something.
Doc: No, its Hill Valley, although I can't imagine hell being much worse!
Einstein whines. Doc takes a candle and goes over to him.
Doc: Oh Einie, I'm sorry boy, the lab is an awful, awful, awful, awful mess!
Doc gets Einstein's basket and he gets inside.
Doc: Atta boy. (to Marty) Obviously the time continuum has been disrupted creating this new temporally venced sequence resulting in this alternative reality.
Marty: English, Doc!
Doc: Here, here, here, let me illustrate.
Doc finds blackboard and stands it up. He picks up some chalk.
Doc: Imagine that this line represents time.....
Doc draws a line on the blackboard.
Doc: ...Here's the present, 1985 (He writes "1985" on the board), the future (he writes "F"), and the past (he writes "Past"). Prior to this point in time... (He points to 1985) ...somewhere in the past, the timeline skewed into this tangent, creating an alternate 1985.
Doc draws the tangent on the board and writes "1985-A" on it.
Doc: Alternate to you, me and Einstein. But reality for everyone else.
Doc goes to the DeLorean and gets a bag out.
Doc: Recognise this? It's the bag the sports book came in. I know, because the receipt is still inside. I found them in the time machine, along with this!
Doc shows Marty what he found. It's the top of 2015 Biff's cane!
Marty: It's the top of Biff's cane, I mean old Biff from the future!
Doc: Correct! It was in the time machine because Biff was in the time machine - with the sports almanac!
Marty: Holy shit!
Doc: You see, whilst we were in the future, Biff got the sports book, stole the time machine, went back in time and gave the book to himself at some point in the past.
Doc draws a line from the "F" on the board to the point where the tangent skewed into 1985-A. He then takes out a copy of the Hill Valley Telegraph, "Hill Valley Man Wins Big At Races". Next to it is a picture of Biff.
Doc: Look! (chuckles in a "how simple!" style) It says, right here, that Biff won his first million betting on a horse race in 1958. He wasn't just lucky, he knew because he had all the race results in the sports almanac. That's how he made his entire fortune! Look in his pocket with a magnifying glass.