long walk back to Hill Valley from here.
Doc: It's still the safest plan. After all, we can't risk sending you back to a populated area, or to a spot that's geographically unknown. You don't want to crash into some tree that once existed in the past. This is all completely open country! So you'll have plenty of run-out space when you arrive. Remember where you're going there are no roads. There's a small cave over there which will be a perfect place to hide the time vehicle. Well, the new time circuit control tubes are warmed up!
Doc starts the DeLorean.
Doc: Time circuits on. I wrote the letter on September 1st, so we'll send you back the very next day. September 2nd, that's a Wednesday. September 2nd, 1885, 8am.
Doc inputs the date and time.
Doc: I get shot on Monday the 7th, so you have 5 days to locate me. According to my letter I'm a blacksmith, so I probably have a shop somewhere. All you have to do is drive the time vehicle directly towards that screen accelerating at 88 miles per hour.
Marty looks at the screen. Underneath is a mural of Indians.
Marty: Wait a minute, Doc. If I drive straight towards the screen, I'll crash into those Indians.
Doc: Marty. You're not thinking 4th dimensionally! You'll instantly be transported to 1885, and those Indians won't even be there.
Marty: Right.
Doc: Well, good luck, for both of our sakes. See you in the future.
Doc pats Marty on his shoulder.
Marty: You mean the past.
Doc: Exactly!
Doc runs to the building with a pistol. It's the same pistol he used in 1985 to try and shoot the Libyans in Part 1.
Doc: Happy trails Marty! Ready Marty?
Marty: Ready!
Doc: Set!
Marty: Hi ho silver.
Doc pulls the trigger and Marty sets off.
Doc: Viya con dios!
Just before he hits the screen and the mural of Indians, he travels through time.
SEPTEMBER 2, 1885
Marty arrives in 1885, only to see a tribe of real Indians heading towards him.
Marty: Indians! Argh!
Marty turns around and heads away from them, but they are chasing him. Marty spots the cave Doc mentioned in 1955.
Marty: The cave!
Marty drives the DeLorean into the cave as the Indians leap over it. They seem to be riding away from something. Marty gets out and discovers what they were riding away from...
Marty: Shit, the cavalry!
Marty runs back into the cave as the Cavalry ride past. They don't see him. Once it is safe, Marty checks the DeLorean. There is an arrow in the side of the car.