The Back to the Future franchise is an American science fiction-comedy-adventure film series written and directed by Robert Zemeckis, produced by Bob Gale and Neil Canton for Steven Spielberg's Amblin Entertainment, and distributed by Universal Pictures. The main plot follow the adventures of a high school student, Marty McFly (Michael J. Fox), and an eccentric scientist, Dr. Emmett L. Brown (Christopher Lloyd), as they use a DeLorean time machine to time travel to different periods in the history of Hill Valley, California.
The first film was the highest-grossing film of 1985 and became an international phenomenon, leading to the second and third films, which were back-to-back film productions, released in 1989 and 1990, respectively. The trilogy was nominated for five Academy Awards all together, winning one (Best Sound Editing).
Back to the Future (1985)
Seventeen-year-old Marty McFly is accidentally sent back in time from 1985 to 1955 in a time machine built from a DeLorean by eccentric scientist Emmett "Doc" Brown, when Marty is attacked by Libyans from whom Doc stole the plutonium that gives the flux capacitor the 1.21 gigawatts it needs to time-travel. Soon after his arrival in 1955, Marty's mother Lorraine falls in love with him, rather than with his father George McFly, threatening to cause a paradox that would result in Marty's nonexistence. Without plutonium to power the time machine, Marty must find the 1955 Doc Brown to help him reunite his parents and return to 1985.
The efforts of Biff Tannen, George's bully and supervisor, further complicate Marty's situation until Marty successfully causes his parents to fall in love and simultaneously convinces George to finally stand up to Biff. Returning to the future via a lightning strike that jump-starts the machine, Marty discovers a vastly improved situation for the McFly family, as Biff is now an auto detailer rather than George's supervisor.
Despite 1955 Doc's insistence on not knowing details of the future, a note Marty leaves in his pocket saves him from being killed by the terrorists. But in the film's final moments, Doc Brown appears in a modified version of the DeLorean and tells Marty and his girlfriend Jennifer Parker that they must travel to the future to fix a problem caused by Marty and Jennifer's kids.
Back to the Future Part II (1989)
The series continues as Doc Brown travels with Marty and Jennifer to the year 2015 where he has discovered Marty's family is in ruins. Marty buys a sports almanac containing the outcomes of 50 years (1950–2000) worth of sporting events. However, Doc catches him and throws the almanac in the trash, where the 2015 Biff Tannen finds it. While Marty and Doc are at Marty's 2015 house, 2015 Biff steals the DeLorean time machine and gives the book to his 1955 self just before he goes to the dance at the end of the first movie.
When Doc and Marty return to 1985, they find that Biff has used the sports almanac's knowledge for financial gain, which allows him to turn Courthouse Square into a 27-story casino, take over Hill Valley, get away with the murder of Marty's father, and later marry Marty's mother. Marty learns that Biff was given the book by 2015 Biff on November 12, 1955, so he and Doc go back to that date in order to steal the almanac from Biff before he can use it to destroy their lives. They accomplish this in a complex fashion, often crossing their own past-selves' paths.
When the duo are about to travel back to 1985, a lightning bolt strikes the DeLorean and activates the time circuits, sending Doc back to 1885 and leaving Marty stranded once again in 1955.
Back to the Future Part III (1990)
After finding out that Doc Brown is trapped in 1885, Marty sets out to find the 1955 Doc to help him fix the DeLorean (which has been waiting for him in a mineshaft for 70 years) and restore it to working order. Learning that Doc gets shot in 1885 by Biff's great-grandfather, Buford "Mad Dog" Tannen, Marty travels back in time to save Doc (who has become a blacksmith) and bring him back to the future. Arriving in the middle of a melee between the United States Cavalry and American Indians, an Indian arrow rips a hole in the Delorean's fuel line, emptying the gas tank and rendering the engine useless.
Inadvertently due to Marty's arrival in 1885, Doc falls in love with schoolteacher Clara Clayton, and considers staying in the past. Marty must convince Doc to come back with him and find a way to get back to his time before it's too late. After several dramatic action scenes involving using a speeding locomotive to push the Delorean to 88 miles per hour (142 km/h), Marty returns to 1985 without Doc Brown, who stayed behind with Clara in 1885. When the Delorean appears in 1985 on the same train track as planned, a modern train destroys the Delorean, with Marty jumping out just in time.
Marty reveals to Jennifer the time travel adventure and they visit the scene of the wreckage of the Delorean. He worries that Doc has been lost in the past forever, when suddenly Doc Brown appears in a new time machine, modeled after a locomotive. He introduces Jennifer and Marty to Clara (to whom he is now married) and his two sons, Jules and Verne. When Marty asks if Doc and his family are going to the future, Doc replies that he's "already been there." Doc's last words of wisdom is that nobody knows their future, so they "must make it a good one." The locomotive flies across the sky and disappears, ending the trilogy.