Because the Trinity killer has apparently re-emerged and killed his wife and daughter - in Nebraska. Of course, Dex (and figment Brian) know this can't be true, because Dexter killed Trinity. Which means that Jonah, Trinity's son, likely killed his sister and mother.
There ensues Dexter as we've never quite seen him before, counseled and urged on by his most brutal, murderous side, i.e., Brian. Dexter tries to hold on to Harry's code, though - as he tells Brian, it's enabled him to survive. And part of it bids him to make sure that Jonah, who lied about his father, really killed his mother and sister.
After Dexter dispatches a pot-grower who steals Dexter's knives and tries to hold Dexter up for money - in a great scene in which Brian->Dexter grabs a pitch fork and kills the blackmailer - Dexter confronts Jonah and realizes that Jonah is not a monster. Against Brian's strenuous objections, Dexter drives away from Jonah and leaves Brian in the dust.
I was hoping for a confrontation between Brian and Harry, but in an ending that's just as good Dexter picks up Harry on the side of the road as he returns to Miami. The code is back in the car and in the driver's seat for Dexter (even though Harry is actually in the passenger's seat).
A brief sojourn in hell for Dexter, who had to let off some kind steam after Sam's death and Dexter killing Nick. But Miami isn't exactly a bed of roses, either. The DDK is still at large, and it's still not clear to me whether he's one person or two.
See also Dexter Season 6 Sneak Preview Review ... Dexter 6.4: Two Numbers and Two Killers Equals? ... Dexter 6.5 and 6.6: Decisive Sam
And see also Dexter Season Five Sneak Preview Review ... Dexter 5.4: Dexter's Conscience ... Dexter 5.8 and Lumen ... Dexter 5.9: He's Getting Healthier ... Dexter 5.10: Monsters -Worse and Better ... Dexter 5.11: Sneak Preview with Spoilers ... Dexter Season 5 Finale: Behind the Curtain
And see also Dexter Season 4: Sneak Preview Review ... The Family Man on Dexter 4.5 ... Dexter on the Couch in 4.6 ... Dexter 4.7: 'He Can't Kill Bambi' ... Dexter 4.8: Great Mistakes ... 4.9: Trinity's Surprising Daughter ... 4.10: More than Trinity ... 4.11: The "Soulless, Anti-Family Schmuck" ... 4.12: Revenges and Recapitulations
See also reviews of Season 3: Season's Happy Endings? ... Double Surprise ... Psychotic Law vs. Sociopath Science ... The Bright, Elusive Butterfly of Dexter ... The True Nature of Miguel ... Si Se Puede on Dexter ... and Dexter 3: Sneak Preview Review
Reviews of Season 2: Dexter's Back: A Preview and Dexter Meets Heroes and 6. Dexter and De-Lila-h and 7. Best Line About Dexter - from Lila and 8. How Will Dexter Get Out of This? and The Plot Gets Tighter and Sharper and Dex, Doakes, and Harry and Deb's Belief Saves Dex and All's ... Well
See also about Season 1: First Place to Dexter
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"a Da Vinci-esque thriller" - New York Daily News
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