Back to the Future Part III

On November 12, 1955, moments after witnessing his apparent death via lightning bolt, Marty McFly (from 1985) learns that Emmett Brown (also from 1985) was transported to 1885 and is trapped. Marty and Doc's 1955 self use the information in Doc's 1885 letter to repair the DMC DeLorean, with 1885 Doc instructing Marty to return to 1985 and leave him be. Marty spots a tombstone with Doc's name, dated six days after the letter, and learns that Doc was killed by Biff Tannen's great-grandfather, Buford. Marty takes a picture of the tombstone and travels to 1885 to save Doc.