Doc takes the DeLorean to 2015, thirty years in the future. Jennifer keeps asking questions about her and Marty's future marriage, causing Doc to use a sleep-inducing generator to knock her out, explaining that no one should know too much of their own future. Doc reveals to Marty that his future identical son, Marty Jr. (Michael J. Fox), was imprisoned after a failed bank robbery in which he was forced to participate by Biff's future grandson Griff Tannen (Thomas F. Wilson). Marty's future daughter Marlene (Michael J. Fox) attempted to break Marty Jr. out, only to be caught and imprisoned herself. Doc explains his plan: to have Marty pose as his future son, refuse to participate in the bank robbery with Griff, and return to 1985 so his future family can live a happy life. Doc gives Marty futuristic clothes so he can look the part, and they leave an unconscious Jennifer in an alley. 