Child porn.

There are different ways to make things scary. There are good suggestions here as far not showing too much, but I wouldn't call that a rule. If you've got a scary image, use it. If you don't, just hint at something that is scarier than what you actually got.

Thinking of a short list of the scariest moments in films I've seen, the scariest are ones where I did see what I was supposed to be scared of, and the film maker made it scary. I think David Lynch is a master at this, but of course his films follow a surreal, often nightmare logic, which can't be applied to everything. But man has he created some scary moments:

The diner scene in "Mulholland Drive"

Bob behind the dresser in "Twin Peaks: Fire Walk With Me"

Bob crawling over the couch in an episode of "Twin Peaks" (yes, television!).

What's interesting about those scenes is that they all take place in well lit situations. But, at least for me, they tap into some primal fears that are hard to articulate.

Another really scary scene I can think of is the end of "Don't Look Now". That was a case of seeing something unexpected and very unsettling.

Another counter example is "The Innocents". You see the ghosts in this film but there is a hazy but it successfully blurs the line between what the audience should accept as imaginary or real.

Anyway, I digress, but I think you have to look at the script you have and decide if you actually have something that is genuinely scary. If it's not that scary by itself you'll need some smoke and mirrors, but if it is, use your cinematic instincts to make it as frightening as possible.

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