A new trailer of "" was shared during the 2009 San Diego Comic Con on Thursday, July 23. Presented before the panel was started, the new footage serves as the promotion to the fourth season. It shows the changes within Dexter as he juggles his newly-found experience as a father, and appearing as the new villain, The Trinity.
In the trailer, Dexter is seen rocking his baby and says to him softly, "Wanna know a secret? Daddy kills people." It continues with Dexter living an apparently normal life on the suburbans with Rita and her kids. "Dexter Morgan has everything he wants, except the one thing he needs...time to kill," so the caption is read. Glimpses of Trinity and how he is about to kill a boy's mother were then shown.