Just finished watching a very effectively scary horrormentary or docuhorror:
Countdown to Zero (2010).
http://www.imdb.com/title/tt1572769/
A documentary about the need for the elimination of nuclear weapons and the increase in global security to prevent any further countries and rogue terrorist groups from making or acquiring any of their own nuclear weapons.
What made it effectively scary was the divulging of the all too many close calls of near misinterpreted attacks between the former Soviet Union and the US. As well as the many instances of lost nuclear missiles that have never been found.
The discussion on the simplicity of creating a bomb from on the commercial market parts in the target city by terrorists was the strongest of the film's warning points.
Some of these well documented historical incidents and almost incidents were already well known and highly publicized scandals but their ad nauseum repetition depicted here in the documentary serves its purpose well as it drives home the point like a sledgehammer buries a railroad nail into the ground to secure the track for the safety of the train and those who ride that train.
A documentary rated at an 8 out of 10.