"Paranormal Activity 3": See the Terrifying New Trailer!

October is almost here, and that means one thing: Bring on the horror movies!

The "Paranormal Activity" franchise returns for its third Halloween in a row this year with a brand new prequel -- showing how sisters Katie and Kristi started being followed by a very ticked off demon.

The brand new trailer, just released today, shows a lot more of the flick than previous teasers, showing kids in peril, "Poltergeist" references, a big fire and some brutal attacks.

The movie is sure to make a killing when it opens October 21.