Jennifer Carpenter who plays serial killer Dexter's sister on the hit Showtime show is scared producers are going to pull an Ashlee Simpson on her AND kill her off!

The brunette beauty who secretly wed costar Michael C. Hall last year is a nervous wreck about the series finale because the details are being kept TOP SECRET!

"There are three pages missing at the end (of the script)," Jennifer confided. "We're not allowed to know what happens.

"I'm scared... (but) this is a show with a serial killer and guess what happens to people around serial killers?

"They die," she said.

"Not only are you gonna die, but you're gonna die in a really messed-up way."

Uh oh.