At the end of season two of the darkly dramatic show Dexter, everything had finally seemed clear to Dexter Morgan (Michael C Hall). He had come to peace with his adopted father Harry (James Remar) and the code he had been raised with to plan his killings and make sure they are justified. He had also, through (many) twists, come away from the discovery of all his victims with no blame, another having been blamed (and killed in the process) of being the Bay Harbor Butcher.
Season Three starts with Dexter adapting Harry's code to suit his personality more, he is still hunting and killing bad people, but it is happening more on his terms then on Harry's. Things are great with Rita (Julie Benz) and her kids, his sister Deb (Jennifer Carpenter) is hitting her stride on the force, and all is well in the world of Dexter Morgan. Of course things cannot stay that way, call it Karma, call it darkness chasing darkness, but in the course of a standard killing Dexter makes a mistake with a victim and it throws his system and life into confusion.
In this season we are introduced to a new character, Assistant District Attorney Miguel Prada (Jimmy Smits), who becomes intertwined with Dexter due to the complications in Dexter's life. Prada's relationship with Dexter is surprising and very different then we would come to expect. On the home front Dexter's life with Rita is in for a shakeup that will mean great changes in their lives and relationship.
All the other characters have some interesting plotlines to explore this year with Deb aggressively pursuing her detective shield and Angel Batista (David Zayas) moving up within the ranks and facing those pressures. Not to be forgotten, Lt. Maria LaGuerta (Lauren Vélez) is trying to keep the peace on her team and face her past with Miguel Prada. Finally forensic specialist Vince Masuka (C. S. Lee) is realizing being the class clown is not the way to have friends or succeed.