You may not know this, but Oct. 21 will mark the end date of the story in Back to the Future 2.
While we don't have huge hologram Jaws, self-lacing sneakers or hoverboards (At least not in any widely available, fun-looking form), we will get a special feature story featuring the likes of Christopher Lloyd reentering his role as Doc Brown.
This teaser is only a brief snippet of what we can expect when Universal rereleases the trilogy of excellent films (though the third is not-quite-as-excellent) on that notable date.
Until then you can just watch this brief trailer trying to unravel its mysteries about how Doc Brown will go about saving the world, and what exactly is causing the danger.
Probably some even more ancient Biff.