[Intro: Marty McFly, 1955 Doc Brown]
It's a small matter of power, Doc. Uh, we need 1.21 gigawatts
1.21 gigawatts... 1.21 gigawatts? How are you gonna generate that much juice?! I'm afraid you're stuck here!
Stuck here?!? Argh! I cannot be stuck here! I got a life in 1985! I got a family! I got a girl!
Is she pretty?
Doc, she's everything to me... please, pleasepleaseplease, you are my only hope... You've never let me down in the past...
You mean in the future?
Hey, and you've always said: "You can accomplish anything if you just put your mind to it."
I said that? That's good advice, but I just don't know how to generate that kind of power, future boy!

[Marty]
Future boy
I'm no future boy
'Cause I think I'm here to stay
What's the future for
If I don't get more than today?
I'm no future boy

I'll never find what I left behind
There's nothing for me here
There's only more of what came before
My future disappeared
Now everything's uncertain
Can't see behind the curtain
I can't go and I don't know
Where this all will lead...
[Interlude: Doc Brown, Marty]
Marty, there is one energy source capable of generating 1.21 gigawatts of electricity: it's a bolt... of lightning!
What did you say?
A bolt... of lightning! Unfortunately, you never know when or where it's ever gonna strike!
We do now
This is it! It says here that the bolt of lightning is going to strike the clocktower at exactly 10:04PM, next Saturday night!

[Doc Brown]
The physics of this problem are perplexing
The muscles in my brain are busy flexing
As a geometric form
Of a pending thunderstorm
Is hard to calculate
But now we have a date
And all my computations must conform!

Eh... if we can somehow harness this lightning, channel it into the Flux Capacitor...
The way to get you back takes an equation
And a meteorological occasion
And then a lightning crack
Becomes a power pack
That's what it's gonna take;
No room for a mistake!
It's the only way to ever get you back!

[Backing Chorus (in rounds)]
The only way to ever get you back!
[Doc Brown, Doc & Backing Chorus, (Backing Chorus), Marty, Marty & Backing Chorus]
Back to the future, boy!
You're the future boy!
And we know we found a way!
Ah, you're the future boy
And it's gonna be okay!
(Ah-ah-ah, Ah-ah-ah...)
I'm the future boy!
(He'll find a way! He'll find a way! He'll find a way! He'll find a waaaaaa-aaaaaay!)
I'm the future boy!