Directed by Robert Zemeckis
Written by Bob Gale
IMDB

Marty shows up in 1955 right after Doc just sent Marty back to 1985.  Marty had just received a letter from 1985 Doc, who has ended up in old west times.  When 1955 Doc and 1985 Marty find out that Doc is about to be assassinated a week after the letter was written, Marty rushes to the past to save him.
I used to not be as big of a fan of this film compared to the first two in the series.  Now I enjoy it more than the second film.  This one has a much tighter script.  It, of course, hits all of the necessary gags that were built in the first two and takes advantage of some great foreshadowing.
Not only is this a better film than Part II, but it is funnier and more emotional like the original.  How can you not love this series of films?  It's one of the best series produced.  It blows Star Wars' ass out of the water, especially with the new trilogy.

9/10