“Natty Knocks” (** out of four) was a mundane horror mystery about a single mother (Danielle Harris) and her children who struggle to survive a serial killer (Bill Moseley) disguised as a cop whose on the prowl on Halloween Eve. Mediocre film wastes the talents of horror icons Harris, Moseley, and also Robert Englund. Film reunites Harris with “Halloween 4” director Dwight H. Little but this film feels like a faint retread.