Hannah McKay is tried for the murder of Sal Price, but poisons herself to escape from custody. Maria LaGuerta arrests Dexter for the murder of Hector Estrada, but his friends, family, and co-workers are quick to stand up for Dexter and believe that LaGuerta was trying to set Dexter up to look like the Bay Harbor Butcher. Debra ultimately is faced with the decision of whether to kill her brother, her only living kin, or take out LaGuerta, a beacon of traditional law and “goodness.”
Dexter meets Clint McKay and then takes him out. Deb relentlessly seeks ways to arrest Hannah McKay against Dexter’s wishes, but when she is drugged and gets into a car crash, Dexter stands up for her and her mission and helps her arrest Hannah. Maria LaGuerta solves the Bay Harbor Butcher mystery and pins the blame correctly on Dexter, but his skilled methods of planting evidence seems to get Tom Matthews convinced and off of his trail. LaGuerta persists however and nearly catches Dexter in the act of taking out Hector Estrada.
Debra finally comes around to understanding and even encouraging Dexter’s Dark Passenger, but Dexter isn’t all too thrilled with who she requests to have killed. Maria LaGuerta seeks the advice of Tom Matthews, but still inches closer to Dexter’s truth. Hannah McKay dreams of Argentina, which inspires Dexter to attempt to envision a life – a normal life. Isaak Sirko demands Dexter’s services, but ends up teaching him a thing or two about love instead before his death.
Sal Price becomes a threat, and then is quickly taken down by Hannah McKay. Maria LaGuerta comes dangerously close to the truth about the real Bay Harbor Butcher. We also learn that sociopaths like Hannah and Dexter can look out for each other and act more human than they could have ever imagined.
Ray Speltzer is arrested and nearly sent to jail for the rest of his life until he is set free to roam the streets once again. Dexter takes him out in attempts to lay to rest his animalistic side, which results in Dexter and Debra’s semi-reconciliation. Meanwhile, Isaak Sirko clues Dexter into the fact that he killed Louis Greene and has made it known that he will kill everyone in Miami Metro in order to avenge Viktor Baskov’s death. Maria LaGuerta lets Deb into her mission to reopen the Bay Harbor Butcher case, but little does she know Deb is only in it to protect her brother.
Debra learns to come to terms with Dexter’s Dark Passenger after she realizes that had she let Dexter do what he does, Ray Speltzer would not have succeeded in killing his latest victim. Maria LaGuerta continues to search for answers about the real identity of the Bay Harbor Butcher after the blood slide found at the site of Travis Marshall’s death is confirmed to be his. The Louis Greene “fire” has officially been put out, but Isaak Sirko has become Dexter’s most formidable victim for season seven, other than himself.
Dexter attempts to cover up the truth of what he is to Debra while also convincing her to help him stage Travis Marshall’s final tableau: a suicide in a burning church. Detective Mike Anderson is shot and killed, opening up this season’s big case for Miami Metro. We are reminded that Deb was about to tell Dexter that she is in love with him when she happened upon his secret. The only thing left for Deb to ask is: “Are you a serial killer?”