In literary criticism, idiot plot refers to "a plot which is kept in motion solely by virtue of the fact that everybody involved is an idiot,"otherwise "they'd immediately figure out everything and the movie would be over."It is a narrative where its conflict comes from characters not recognizing, or not being told, key information that would resolve the conflict, often because of plot contrivance. The only thing that prevents the conflict's resolution is the character's constant avoidance or obliviousness of it throughout the plot, even if it was already obvious to the viewer, so the characters are all "idiots" in that they are too obtuse to simply resolve the conflict immediately.
(Taken from Wikipedia... Credit them not me.)
Dude! You saw School Days? MAN! THE IDIOT PLOT WAS STRONG IN THAT SHOW.