The movie continues where the last one with Marty stuck in 1955. But Doc Brown sent him a letter from 1855 through Western Union, that told him that after the Delorean was struck by lightning he was sent to 1855 and was unable to repair it, but has managed to bury it somewhere, where Marty can get to it in 1955 and hopefully the younger version of himself can repair it so he can drive it back to 1985 and then destroy it. But after finding it, Marty discovers that shortly after sending the letter Doc would be shot by an outlaw, Mad Dog Tannen. Marty then goes back to 1885 to save him and meets his ancestors. After finding the Doc, they were about to leave when Marty told the Doc that upon arriving the Delorean's gas tank was punctured, so they don't have any gasoline to run the car, which means they have to find some way to get the car to 88 mph. They decide to try pushing it with a locomotive. And things are fine except for the fact that Tannen, who had it in for Doc, now has it for Marty and has challenged him to gunfight on the day that they are going to leave, and Doc is smitten with Clara Clayton, the new school teacher.