Marty travels back to 1885 in order to rescue Doc Brown whom he believes is stranded there. Upon arrival Marty is caught in the middle of a conflict and damages the fuel tank making the time travel unable to achieve the 88 mph that it requires to return the pair to 1985. During the engineering of an alternative form of acceleration Marty has a run in with the Biff of 1885 and the first McFlys to live in Hill Valley.
Doc Brown meets and falls in love with the town's new teacher despite the fact that she was supposed to die if it was not for his intervention which runs contrary to his belief that time travels should alter the the events of the past. Doc Brown and Marty conclude that they can get the time machine moving fast enough if they high jack a train and push it to it's maximum speed. Their plan does not work entirely as intended.