Author's note, please read: I do not own the Discworld stories, I do not own Back to the Future.
I was inspired to write this as i have always wondered what might have happened...
Carcer smiled.
'Mister Vimes...'
'What?'
'I've got three knives.'
The lightning struck.
Doc. Brown was hanging perilously from the lightning conducting cable, desperately trying to reconnect it as the seconds passed with enormous speed. Back along the street in the De Lorean, Marty was trying in vain to start the car, the timer hit zero but the engine would not turn over. Out of sheer frustration, he hit his head against the steering wheel. Miraculously, the car sprung into life and he wasted no time in stepping on the gas. As he sped down the street, up on the roof, Doc Brown had just connected the wire as he noticed, to his horror, a small break at street level. In order for the car to receive the 1.21 gigawatts of electricity required to power the time circuit, the cable had to be connected at the time the lightning struck. In a daring attempt to fix the break, the Doc grabbed hold of the wire and slid down it to the ground. There he fixed the break in time but, as the car passed him, he stumbled into it, falling in through the window and his foot smashing into the time circuits, the dates and numbers scrambled, but it was too late for anyone to do anything because, just at that moment,
The lightning struck.