Dexter is finding it hard to have closure on killing his brother. There is a new FBI agent to head the "Bay Harbor Butcher" case. Debra is finding it tough to put the past behind her.

Rita's estranged mother visits and senses something is wrong with Dexter. Masuka thinks he's developed a lead in the Bay Harbor Butcher case, which has Dexter concerned. Angel's interrogation of a witness crosses a line.

Dexter discovers that the man who murdered his mother in front of him as a boy is still alive and confronts the killer as part of his recovery from addiction - but he also discovers that old impulses die hard.

A copy-cat killer follows the lead of the "Bay Harbor Butcher." Dexter must destroy an incriminating surveillance video.

Dexter manages to get Doakes off his back. He devises a plan to get the police in another direction. Lila and Dex's relationship intensifies, and he has some interaction with Rita and the kids.