Dexter TV Series: The Complete Sixth Season. The explosively popular DEXTER is back with a vengeance for a sixth season of startling suspense and unexpected twists. It’s been a year since last season’s shocking and heartbreaking conclusion, and mild mannered criminologist-cum-grisly serial killer Dexter Morgan has come to terms with who he is. But his existence is shattered when he crosses paths with an enemy unlike any he’s faced before. A delusional religious zealot with unflinching convictions, this new adversary soon draws Dexter into a dangerous game that could well end in disaster.