The one thing I like about the Dexter series is that it's different enough from year to year. When this new season begins he's caring for his two-year-old son--and he seems to have a strong emotional attachment to the boy. He's hired Angel Batista's sister, Jamie, to be a nanny, and that's working out. The first killing he does is with two paramedics who have been killing people to harvest their organs. Then, he goes off to his twenty-year High School reunion, where he's regarded as something of a celebrity because of the high-profile murder of his wife, Rita. Everyone knows who he is-- which poses a problem since the only reason he's shown up at the reunion is to kill a fellow classmate who murdered his wife some years before. Meanwhile, Batista and Maria LaGuerta, who has married the end of last season are now divorced. And Dexter's sister Debra breaks up with her boyfriend, Quinn, and is promoted to Lieutenant, which makes things a bit more complicated for her.
The murders they are all investigating this time revolve around two guys who want to bring forth the Biblical apocalypse. These are Professor Geller (Edward James Olmos of BATTLESTAR GALACTICA) and Travis (Colin Hanks), a former student. They think that by staging these scenes in Revelations, like the Four Horsemen, they'll bring about it actually happening. Dexter discovers that Travis is one of the killers but keeps from killing him because it seems as if he's just a misguided follower.
Also, there are some reminders of past seasons. In one episode the wife and daughter of the Trinity Killer is killed and the surviving son says it was his father who returned and did it. But Dexter had killed him so he knows the son is lying. Dexter sort of goes a little nuts here and takes off from work for a week to check this out, in Nevada, a long way from Miami. However, instead of his father appearing to advise him, it's his dead brother, the infamous Ice Truck Killer. During this time Dexter kills a motel owner who steals his knives and tries to blackmail him. But Dexter ends of getting a grip on himself and returning to "normal".
There are some great twists that happens in the last few episodes and the cliffhanger ending is something we've all been waiting for. It's something that we knew would inevitably happen--it will surely make Season Seven VERY different.