Marty McFly (Michael J Fox) is a teenager in Hill Valley, California in 1985 - and then in 1955. Dr Emmett Brown's time machine has flung Marty 30 years back in time and he's stranded there unless the 1955 Doc Brown can help him. Worse: Marty's own mother, here a high school teenager, is falling for him instead of his father.
It sounds like a clichéd science fiction movie that could only appeal to fans of the genre - but that couldn't be more wrong. A huge hit, it appealed across the board for its invention, its exuberant energy, and the famous finale - so tense, so very exciting and yet able to make you gasp and laugh at the same time.
Looking back at it now, it seems less subtle than it did on release and you can't help but recognise how carefully the story sets out to manipulate you. Every scene, every line works but then later you see how you were set up: nobody says anything that doesn't become important to the plot later. That should be terrible, but it's done so very well that it's a treat. It's undeniably formulaic but so outstandingly executed that it vindicates the formula.
No surprise then that there were two sequels (and subsequent video releases of the film had the line "To Be Continued" added to the closing moments). They are good but not quite to the standard of this gem.