Back to the Future Part II (1989) follows Marty, Doc, and Jennifer as they travel to 2015 to save Marty’s kids, but their interference lets Biff steal a sports almanac and create a corrupt alternate 1985. To fix history, Marty and Doc return to 1955, weaving through events of the first film in a fast-paced, layered adventure about greed, fate, and the ripple effects of time travel.