Dexter Episode Details!

Episode 4.11 - "Hello, Dexter Morgan"
Dogged Debra's investigative skills have the department on the verge of not only nailing the Trinity Killer, but ultimately exposing Dexter's clandestine and deadly side job. It would also deprive him of the opportunity to deal with the serial murderer in his own way. At home, Rita's decision to confide in her husband doesn't garner the result for which she hoped. And back in the squad room, a breach of ethics has Batista and LaGuerta in hot water.

Episode 4.12 - "The Getaway"
In the Season 4 finale, the police close in on the Trinity Killer, who cautions Dexter to keep away. But Dexter is willing to do whatever he can to get his man, legal or not. Meanwhile, LaGuerta and Batista must answer for their breach of ethics; and Debra becomes privy to something she's not sure she wanted to know.

Source: TV Guide