Dexter Morgan investigates The Trinity Killer and learns that he is the professor and family man Arthur Mitchell, married with two children. Trinity hides behind a well-kept mask, and getting behind that facade will require some extra prodding on Dexter's part. Dexter is intrigued with the seemingly real affection that Arthur has for his family and decides to get closer to the serial killer. He goes to the Sacred Fellowship and he introduces himself as Kyle Butler.
Meanwhile, Rita forces Dexter to go with her to a marriage therapist expecting to resolve her issues with Dexter.
Debra believes that Nikki Wald had killed Frank Lundy and she intends to commit perjury against the junkie. She becomes frustrated when she finds herself shut out from her own case. She considers bending the rules in the name of justice, risking her career in the process. However, she changes her mind.
Maria and Angel regret the disclosure to Deputy Chief Thomas Matthews about their relationship and they deliver affidavit that they are not dating each other. They realize that by playing by the rules they may have painted themselves into a corner. And when the friction between Rita and Dexter comes to a head, Dexter gleans relationship advice from a most unlikely source.
|If I Had a Hammer - Refers to the title of a folk song of the same name written in 1949 by Pete Seeger. It also mainly refers to the hammer that Trinity killer uses to kill his latest victim which Dexter wants to "have" it in order to examines for clue. But in the ending, Trinity gives it to him by himself.|
|Dexter uses the alias "Kyle Butler" when he introduces himself to Arthur Mitchell|
|"I'm perfectly comfortable with bodily fluids. |
Blood, snot, tears. But the emotions that go along with them - not so much"
- Dexter, to himself