Finding some conclusive supporting material about the (as yet unsolved) Voynich Manuscript.
Either, enough information to decode a possible cypher, or proof that it is an elaborate troll/hoax/joke.
Could be the 'Rosetta Stone moment' of the modern era.
Twilight Zone movie.
Watched alone on dark night.
The part when the lady visits the house, where the family is terrified of putting a foot out of line.
That has the most distasteful feeling of dread. Really well done, not for kids!