Back to the Future Part III is a 1990 American science fiction Western film, and the third and final installment of the Back to the Future trilogy. On November 12, 1955, Marty McFly discovers that his friend, Dr. Emmett Brown, had become trapped in 1885. Marty, with the 1955 Doc, uses the information in Doc’s 1885 letter to locate and repair the DeLorean. Marty spots a tombstone with Doc’s name, dated six days after the letter. Learning that Doc was killed by Biff Tannen’s great-grandfather, Buford “Mad Dog” Tannen, Marty travels back to 1885 to save Doc.
Enjoying a peaceable existence in 1885, Doctor Emmet Brown is about to be killed by Buford “Mad Dog” Tannen. Marty McFly travels back in time to save his friend.