I stumbled across this movie while looking for the 80's TV Show The Day After. Someone made a comment that Threads made The Day After look weak, so I had to check it out. I don't want to give anything away, but this movie is awesome. I don't think there is a threat of total world destruction like this, but a global pandemic or biological attack could probably do the same.
As of late, I have had a knack for selecting movies with abnormal endings, and this one fits the bill. Set in Sheffield, England, the movie follows a few characters through the trials and tribulations of GLOBAL THERMAL NUCLEAR WAR. It is, without a doubt, one of the most depressing films I have ever seen. The Science Film-type narrations add to the effect.
Like I said, I don't want to give anything away, but if you watch the movie, pay attention to the manner in which the media is controlled and handles the whole crises.