| Episode cast overview, first billed only: | |||
| Michael C. Hall | ... | Dexter Morgan | |
| Julie Benz | ... | Rita Morgan | |
| Jennifer Carpenter | ... | Debra Morgan | |
| Desmond Harrington | ... | Det. Joseph 'Joey' Quinn | |
| C.S. Lee | ... | Vince Masuka | |
| Luna Lauren Velez | ... | Lt. Maria LaGuerta (as Lauren Velez) | |
| David Zayas | ... | Sgt. Angel Batista | |
| James Remar | ... | Harry Morgan (credit only) | |
| John Lithgow | ... | Arthur Mitchell | |
| Geoff Pierson | ... | Deputy Chief Tom Matthews | |
| Courtney Ford | ... | Christine Hill | |
| Julia Campbell | ... | Sally Mitchell | |
| Roma Maffia | ... | Marriage Therapist | |
| Brando Eaton | ... | Jonah Mitchell | |
| Vanessa Marano | ... | Rebecca Mitchell | |
Dexter knows it's only a matter of time before Miami Metro discovers the Trinity Killer's latest handiwork. Therefore, he has to work doubly hard to stay one step ahead of their investigation. Under the alias of 'Kyle Butler', Dexter has begun to realize that the closer he gets to Trinity, the more he stands to learn from this very different beast. As the friendly building contractor Arthur Mitchell, the Trinity Killer hides behind a well-kept mask; and getting behind that facade will require some extra prodding on Dexter's part. Meanwhile, Debra 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. LaGuerta and Batista come to regret a major decision, and 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.
Dexter investigates Trinity and learns that he is the professor and family man Arthur Mitchell, married with two children. Dexter is intrigued with the real affection of Trinity for his family and decides to get closer to the serial-killer. He goes to the Sacred Fellowship that helps people 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 Lundy and she is intended to commit perjury against the junkie. Maria and Angel regret the disclosure to Deputy Chief Tom Matthews about their relationship and they deliver affidavit that they are not dating each other.
"If I Had a Hammer" is a "stalled" episode of Dexter. Rita is annoying and now she decides to go to a marriage therapist. I do not know how often this procedure happens in the American society but from an outsider, this decision is quite ridiculous. Dexter studies Trinity but does not kill him, otherwise the season would have to come to an end. Why does he need to be intrigued with the affection of the serial-killer for his family seems to be only to buy time and extend the season for six more shows. My vote is seven.
Title (Brazil): "Se Eu Tivesse um Martelo" ("If I Had a Hammer")