Quick recap
In 1955, Marty learns that Doc was sent to 1885 and that Buford Tannen will kill him six days after he writes a letter. With the 1955 Doc's help, he repairs the DeLorean and travels to the Old West to save him. There Doc falls for schoolteacher Clara Clayton, and Marty has to face Buford in a duel. Without gasoline to reach 88 mph, the pair use a steam locomotive to push the car. Back in 1985, Marty sees his own future change, and Doc reappears in a locomotive that travels through time.
