Back to the Future Part II is a 1989 American science-fiction adventure comedy film directed by Robert Zemeckis and written by Bob Gale. It is the sequel to the 1985 film Back to the Future and the second installment in the Back to the Future trilogy. The film stars Michael J. Fox, Christopher Lloyd, Thomas F. Wilson and Lea Thompson and continues immediately following the original film. After repairing the damage to history done by his previous time travel adventures, Marty McFly (Fox) and his friend Dr. Emmett "Doc" Brown (Lloyd) travel to 2015 to prevent McFly's future son from ending up imprisoned. However, their presence allows Biff Tannen (Wilson) to steal Doc's DeLorean time machine and travel to 1955, where he alters history by making his younger self wealthy.
The film was produced on a $40 million budget and was filmed back-to-back with its sequel, Part III. Filming began in February 1989 after two years were spent building the sets and writing the scripts. Two actors from the first film, Crispin Glover and Claudia Wells, did not return for the final two. While Elisabeth Shue was recast in the role of Wells' character, Jennifer, Glover's character, George McFly, was not only minimized in the plot, but was obscured and recreated with another actor. Glover successfully sued both Zemeckis and producer Bob Gale, changing how producers can deal with the departure and replacement of actors in a role. Back to the Future Part II was also a ground-breaking project for effects studio Industrial Light & Magic (ILM); in addition to digital compositing, ILM used the VistaGlide motion control camera system, which allowed an actor to portray multiple characters simultaneously on-screen without sacrificing camera movement.
Back to the Future Part II was released by Universal Pictures on November 22, 1989. The film grossed over $331 million worldwide, making it the third-highest-grossing film of 1989.
On October 5, 1985, Dr. Emmett "Doc" Brown arrives in his flying time machine and persuades Marty McFly and his girlfriend, Jennifer Parker, to come back to the future with him to help their future children. Biff Tannen witnesses their departure. They arrive on October 21, 2015, where Doc electronically knocks out Jennifer and leaves her asleep in an alley, explaining that she should not have too much knowledge of future events. He has Marty pose as his own son to refuse an offer to participate in a robbery with Biff's grandson, Griff.