This looks to be a season exploring Dexter's spirituality, or lack thereof.
-We are several months past the events of last season. Angel is divorced again (can't remember if that happened last season, but don't remember it), Deb is still dating Douchebag, and Harrison is gearing up for preschool.
-Angel recommends a highly regarded Catholic preschool for Harrison, but Dexter is unsure with all the crucifics everywhere. He decides that just because he doesn't believe in God, it doesn't mean Harrison shouldn't have the option.
-Masuka is teaching a college class and has a group of interns now. Everyone is surprised when he doesn't hire the cute blond, but opts for the lab geek.
-Dexter goes to his high school reunion and gets lucky in more ways than one.
-And we have the Big Bad set up for this season. A group I'll call the Alpha and Omega Cult until they get a name. They are busting out ritual killings in the name of the LOWARD! Should be interesting to see what happens between them and Dexter's crisis of faith.
Technically, Bergen isn't a "new" member of the legal team. She's playing Schmidt, the third partner of Crane, Poole, and Schmidt. We haven't met Schmidt yet, but she's probably a veteran (since she's a partner). EDIT: Nevermind...