Season 6 of Showtime's "Dexter" returns tonight with a fresh and freaky theme and a compelling new list of guest stars.

I don't think I'll ever get tired of this show. Even when I think I've grown ambivalent, it only takes one episode to pull me back into serial killer Dexter Morgan's (Michael C. Hall) tense and exhausting life of baby-raising, blood spatter analysis, and bad guy-killing.

The new season adds Colin Hanks and Edward James Olmos as religious zealots who are trying to ... actually, I watched three episodes and I'm still not sure what they are trying to do, but they are most definitely up to no good.

Also in the cast this season is Mos Def, who is credited on the show simply as Mos (when did that happen?). Mos plays Brother Sam, an ex-con who has supposedly found religion, but Dexter is skeptical. Is Brother Sam "tending his flock" to keep them out of trouble or running some kind of scam? (The part brings to mind Walton Goggins as Boyd in FX's "Justified.")