In this, the second of the BTTF Trilogy, Marty McFly is dragged to the future by his best friend, Dr. Emmett "Doc" Brown in a bid to save his son from a life in prison. Things seem to go well, until Biff of the future discovers the time machine and Doc and Marty find themselves stuck in what can only be described as Hell Valley! With time running out, can our heroes find out what's gone wrong, and when?