No sooner has Marty McFly (Fox) returned to 1985, than Doc Brown (Lloyd) turns up to whisk him and perfunctory romantic interest Jennifer (Shue) off to 2015, in order to prevent grown-up Marty's kids going to jail. Meanwhile, mean old man Biff Tannen (Wilson) picks up an almanac of sports results, borrows the DeLorean, and heads back to the '50s to make himself rich and turn Hill valley into hell on earth. With Bob Gale, Zemeckis has fashioned a script whose complex twists, ironies and paradoxes amply compensate for the somewhat juvenile nature of the action itself. Kids will love the wham-bang-wallop, but adults will probably be more concerned with trying to fathom exactly what is going on, how and why. It's impressive entertainment, and best of all, it never degenerates into Spielbergian sentimentality: you can laugh, be thrilled and think without feeling embarrassed.