Manny The Movie Guy /

The fourth installment in the super-popular "Paranormal Activity" franchise will scare viewers on Oct. 19, and today, we heard that Paramount has picked a writer.

Zack Estrin, writer/executive producer on ABC's "The River" is set to pen "Paranormal Activity 4." Having "Paranormal" producer Jason Blum and creator Oren Peli as executive producers of "The River" surely helped matters. They are probably impressed with Estrin's talent in giving folks the heebie jeebies.

"Paranormal Activity" is one of the most profitable franchises ever! Just look at the math: the first "Paranormal Activity" was made for $15,000 and grossed $193.4 million worldwide!

"Paranormal Activity 2" cost $3 million to make and eventually sold $177.5 million worth of box-office tickets worldwide.

The third "Paranormal" cost about $5 million and made $202.2 million worldwide.

Can you see the pattern here? So how much will "Paranormal Activity 4" cost? $10 million maybe? It can't be that much! There are no-name stars and no heavy special effects trickery needed.

The plot is still under lock and key but if we're going by the narrative thread of the franchise, the fourth installment will be a continuation of what was revealed in "Paranormal Activity 3."

I enjoyed this franchise -- the most profitable found-footage series yet! Take a look at my interviews with the "Paranormal Activity" folks through the years:

"Paranormal Activity" Interview with Micah and Katie! See What They Said About Sequel Plans!

Katie Speaks! My Fun "Paranormal Activity 2" Interview with Katie Featherston

Everything You Wanted to Know About "Paranormal Activity 3!" Directors Henry Joost and Ariel Schulman Talk About the Trailer, the "Fan Cam," and the Possible Sequel!