Dexter investigates who shot Brother Sam. Meanwhile, Homicide interrogates the woman who Quinn slept with who is involved in the Doomsday Killer case.
With the help of his newfound friend Brother Sam, Dexter wonders if there is light within him to counter the darkness, while the search for the Doomsday Killers takes him in a new direction; Batista and Quinn pay a visit to the university where Professor Gellar taught; due to departmental regulations following the shooting, Debra is forced to begin therapy.moreless
The team investigates murders that have a religious undertone to them.
Dexter faces a serial killer from his past; Debra has problems with her new position and Travis with Gellar think of their next move.
In order to solve the mysterious murders, Homicide asks for the help of Brother Sam, who Dexter knows used to be a serial killer. Debra has two proposals, one personal and one job-related.moreless
Dexter uses his 20 year high school reunion as a chance to hunt the prom king. It's going fine until he is called to the scene of a vicious faith-based murder leaving him with questions about what he wants to pass on to Harrison. Debra who is finally in a good place with her relationship with Quinn and her job becomes an unexpected hero.
With imminent danger on the horizon, Dexter makes one last bid to eliminate Arthur from his wife, dodging all the bullets that come with the challenge. Debra makes a shocking revelation about the background of Rudy Cooper, The Ice Truck Killer. Angel and Maria continue to discover problems with their relationship. Amongst all this, the season ends with a shocking but inevitable twist.moreless