Contemporary high schooler Marty McFly (Michael J. Fox) doesn't have the most pleasant of lives. Browbeaten by his principal at school, Marty must also endure the acrimonious relationship between his nerdy father (Crispin Glover) and his lovely mother (Lea Thompson), who in turn suffer the bullying of middle-aged jerk Biff (Thomas F. Wilson), Marty's dad's supervisor. The one balm in Marty's life is his friendship with eccentric scientist Doc (Christopher Lloyd), who at present is working on a time machine. Accidentally zapped back into the 1950s, Marty inadvertently interferes with the budding romance of his now-teenaged parents. Our hero must now reunite his parents-to-be, lest he cease to exist in the 1980s. It won't be easy, especially with the loutish Biff, now also a teenager, complicating matters.