With Marty McFly's parents back together and back in his own time of 1985. He thought that his ordeal of time traveling was over. What he does not know is that it was just the beginning. As Dr. Emmett L Brown says that he has to come to the future with him. Marty and his girlfriend Jennifer come with Doc to the year 2015 where his future family is about to enter turmoil when Marty's son Marty Jr. is about to be in a robbery, Marty and Doc formulate a plan to prevent the robbery from taking place, as they succeed in their mission Marty buys a book called "Grey's Sports Almanac" which is a futuristic sports statistics book. When Doc throws it away, former school bully named Biff Tannen picks it up and discovers about Doc's time machine. Biff then steals the time machine. When he brings it back and Doc and Marty with his girlfriend Jennifer go back to 1985, things were not right. Then both Marty and Doc realize that Biff altered time, Biff is rich, and married to Marty's mother Lorainne. The only way to prevent this from happening, Marty and Doc have to go to 1955, to steal the Almanac from Biff.