The Horror Pivot-Moment

Here's something I've been thinking of lately.

Have a look at this: it's an episode of the original Twilight Zone, "Living Doll," featuring Telly Savalas as an abusive dad who meets a doll with a mind of its own.

There's a moment about three minutes in, where Telly holds the harmless-looking doll for the first time and it tells him, "My name is Talky Tina, and I don't think I like you."

And it's that moment- that one instant of perfect shivery weirdness- that sells the whole thing. All the rest of the episode is just working out the details and consequences of that one moment; it's dull by comparison.

(Not to say that it's a dull episode! It's not. But the emotional impact seems to happen right here at the beginning, where we're suddenly presented with the introduction of weirdness to a normal, if awful, suburban world.)

Is there a word for this? Something like the opposite of "climax" for plot, where it makes an emotional impact at the beginning and plays out the details from there?