Lair of the White Worm: Chapter XXIVa
From the book. "The more Mimi thought over the late events, the more puzzled she was. What did it all mean--what could it mean, except that there was an error of fact somewhere. Could it be possible, that some of them--all of them had been mistaken, that there had been no White Worm at all? On either side of her was, a belief impossible of reception. Not to believe in what seemed apparent was to destroy the very foundations of belief . . ."
The same occurs to some extent in the film. The disbelief, followed by the attempt to put the pieces of the puzzle together, in order to plot some sort of plan of offense and defense.