Genre: Mystery

Dexter uses lessons he learned from Brother Sam to follow up on some new leads in the Doomsday investigation; Debra butts heads with Captain LaGuerta over the case of a dead call girl.

Dexter finds himself teamed up with a fellow Dark Passenger when he takes a road trip to Nebraska to tie up some loose ends from the past; Debra deals with the complications of her promotion as she leads the Doomsday investigation.

Dexter is caught up in a very personal case that awakens the needs of his Dark Passenger; Debra feels overwhelmed by her new Lieutenant duties, made all the more complicated when she finds out Quinn slept with a witness in the Doomsday 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.