to save Doc (who has become a blacksmith) and bring him back to the future. Arriving in the middle of a chase between the United States Cavalry and American Indians, Marty is forced to flee to a cave, discovering the DeLorean's fuel line is torn. Marty convinces Doc to come back with him and find a way to get back to his time before it is too late, but Doc is smitten after saving schoolteacher Clara Clayton. After running afoul of and defeating Buford Tannen and several dramatic action scenes involving using a speeding locomotive to push the DeLorean to , Marty returns to 1985 without Doc Brown. When the DeLorean appears in 1985, a modern train destroys it, with Marty barely escaping. Reuniting with Jennifer, Marty avoids a street race and the two visit the scene of the wreckage of the DeLorean. Suddenly, Doc, Clara and their children appear in a time-travelling steam locomotive. Doc reminds Marty and Jennifer that "[their] future is whatever [they] make it", so they must "make it a good one". The locomotive lifts off the tracks and departs from 1985, ending the trilogy. Future Co-writer and director Robert Zemeckis, who has final rights to all films in the Back to the Future franchise, has stated that he will block all attempts to remake or reboot the original film. Co-writer Bob Gale commented that he did not wish to see another film in the series without the Marty McFly character nor any other actor than Michael J. Fox playing him, while acknowledging that Fox's current health condition would make this impossible. He illustrated this at a 2008 fan convention in Florida, stating: "The idea of making another Back to the Future movie without Michael J. Fox – you know, that's like saying, 'I'm going to cook you a steak dinner and I'm going to hold the beef. Gale also said that the Telltale video-game adaptation is the closest thing to what a fourth film could be like. In an interview on October 21, 2015, the day of Marty McFly's purported arrival in the future, Christopher Lloyd stated that he would consider making a fourth film under the condition that the original cast and creative team returned, along with a story "worth telling". The same day, Lloyd reprised his role as Doc Brown in a brief segment in which the character returns with a special message