Do you have the courage to sacrifice everything?

So asks Walter Bishop in the following Fringe series finale promo, which features numerous scenes from this Friday's two-hour episode and which makes one thing very clear: viewers will need to watch with a box or Kleenex. Or two dozen.

With one final battle against the Observers looming, Fox has unveiled one final, extended teaser that is a must-watch for any fan of this impressive drama. Will everyone make it out alive?

We're afraid to ask...

Matt Richenthal is the Editor in Chief of TV Fanatic. Follow him on Twitter and on Google+.