Back-to-back Scream IV stories? Well aren’t you a lucky (or maybe just annoyed?) dog! Shooting is already in progress down at Ann Arbor, Michigan, yet casting continues to change on drastic levels due to last second script changes (on-set script changes are common practice, so un-bunch your panties already, jeez) by Kevin Williamson. So who is the latest batch of teens to join Wes Craven’s beginning of a new trilogy? Read on for the deets. Dimension Films wants this sucker in theaters by April 15, 2011.
Adam Brody (Jennifer’s Body, The Ring), Marley Shelton (Planet Terror, Sin City) and Erik Knudsen (Saw II, Beastly) have joined the cast of Scream 4, which reunites Wes Craven with Kevin Williamson, who kicked off a horror movie revival with his Scream script in 1996, reports Heat Vision.

The new film sees the return of cast members Neve Campbell, Courteney Cox and David Arquette, along with a group of new stars – Emma Roberts, Hayden Panettiere, Rory Culkin, Nico Tortorella, Anthony Anderson, and Marielle Jaffe – who can hopefully stay alive long enough to figure out the new rules to this one-of-a-kind horror franchise.

Brody will play a cop recently graduated from college who was raised on the “CSI” TV series.

Shelton will play a deputy who knew Campbell’s character in high school, adds the site. Lake Bell had been in negotiations for the role.

Knudsen will have a role similar to the one played by Jamie Kennedy in the first two installments, a character who is familiar with horror movie conventions and a provider of comic relief.

To preserve the identity of the killer, Craven and Williamson are operating under several layers of secrecy, including not sending the script to agencies. At a table read last week, the actors were told to stop reading at page 75 to prevent even those already cast in the film from knowing the climax.

Pictured: Adam Brody, left, Marley Shelton, and Erik Knudsen