Back to the Future Part III

On November 12, 1955, moments after witnessing Doc vanish with the DeLorean via lightning bolt, Marty McFly (from 1985) learns that Dr. Emmett Brown (also from 1985) was transported to 1885 and is trapped. Marty and the 1955 Doc use the information in Doc's 1885 letter to find and repair the 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 photographs the tombstone and travels to 1885 to save Doc.