On the last day before summer vacations Michael receives a glowing, but anonymous, love-letter. He suspects, or better: hopes, it's from Deborah, the girl he's after since a while, but who dates college students only. However she shows him a cold shoulder again. So his and her best friend Toni advises him to write her an anonymous letter in return. However these letters get in the wrong hands and cause lots of confusion in their families, until it's revealed, who wrote which letter to whom.

Marty McFly has only just got back from the past, when he is once again picked up by Dr. Emmett Brown and sent through time to the future. Marty's job in the future is to pose as his son to prevent him being thrown in prison. Unfortunately, things get worse when the future changes the present.

Marty McFly, a typical American teenager of the Eighties, is accidentally sent back to 1955 in a plutonium-powered DeLorean "time machine" invented by slightly mad scientist. During his often hysterical, always amazing trip back in time, Marty must make certain his teenage parents-to-be meet and fall in love - so he can get back to the future.