Quick recap
Debra makes lieutenant over Batista, and LaGuerta rises to captain. Miami gets killings staged from the Book of Revelation. Dexter tracks down Professor James Gellar and his student Travis Marshall, who says he acts on his mentor's orders. Meanwhile, Dexter befriends Brother Sam, a reformed ex-con, who gets shot by one of his own workers; Dexter doesn't forgive the shooter. He learns Travis killed Gellar three years earlier and the professor only lived in Travis's head. Travis kidnaps Harrison, Dexter saves his son and takes Travis to an abandoned church. In therapy, Debra realizes she's in love with her brother. In the end, she walks into the church and sees Dexter drive the knife into Travis.
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